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pH
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For other uses, see PH (disambiguation).
Lemon juice tastes sour because it contains 5% to 6% citric acid and has a pH of 2.2. (high acidity)
Acids and bases
pH
Reaction
Titration
Extraction
Dissociation constant (acid)
Acid strength
Acidity function
Buffer solutions
Proton affinity
Self-ionization of water
Amphoterism
Acid types
Brønsted
Lewis
Mineral
Organic
Strong
Superacids
Weak
Monobasic acid
Dibasic acid
Tribasic acid
Solid
Base types
Brønsted
Lewis
Organic
Strong
Superbases
Non-nucleophilic
Weak
v
t
e
In chemistry, pH (/piːˈ(h)eɪtʃ/) (potential of hydrogen) is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the molar concentration, measured in units of moles per liter, of hydrogen ions. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion.[1] Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH 7 (25°C), being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively.[2]
pH measurements are important in agronomy, medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, nutrition, water treatment and water purification, as well as many other applications.
The pH scale is traceable to a set of standard solutions whose pH is established by international agreement.[3] Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator.
Contents
[hide]
1 History
2 Definition and measurement
2.1 pH
2.2 p[H]
2.3 pH indicators
2.4 pOH
2.5 Extremes of pH
2.6 Non-aqueous solutions
3 Applications
3.1 pH in soil
3.1.1 Classification of soil pH ranges
3.2 pH in nature
3.3 Seawater
3.4 Living systems
4 Calculations of pH
4.1 Strong acids and bases
4.2 Weak acids and bases
4.3 General method
5 See also
6 References
7 External links
History
The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909[4] and revised to the modern pH in 1924 to accommodate definitions and measurements in terms of electrochemical cells. In the first papers, the notation had the "H" as a subscript to the lowercase "p", as so: pH.
The exact meaning of the "p" in "pH" is disputed, but according to the Carlsberg Foundation, pH stands for "power of hydrogen".[5] It has also been suggested that the "p" stands for the German Potenz (meaning "power"), others refer to French puissance (also meaning "power", based on the fact that the Carlsberg Laboratory was French-speaking). Another suggestion is that the "p" stands for the Latin terms pondus hydrogenii (quantity of hydrogen), potentia hydrogenii (capacity of hydrogen), or potential hydrogen. It is also suggested that Sørensen used the letters "p" and "q" (commonly paired letters in mathematics) simply to label the test solution (p) and the reference solution (q).[6] Currently in chemistry, the p stands for "decimal cologarithm of", and is also used in the term pKa, used for acid dissociation constants.[7]
Definition and measurement
pH
pH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution.[3]
p H = − log 10  ( a H + ) = log 10  ( 1 a H + ) {\displaystyle \mathrm {pH} =-\log _{10}(a_{{\textrm {H}}^{+}})=\log _{10}\left({\frac {1}{a_{{\textrm {H}}^{+}}}}\right)}
For example, a solution with a hydrogen ion activity of 5×10−6 = 1/(2×105) (at that level essentially the number of moles of hydrogen ions per liter of solution) has a pH of log10(2×105) = 5.3. For a commonplace example based on the facts that the masses of a mole of water, a mole of hydrogen ions, and a mole of hydroxide ions are respectively 18 g, 1 g, and 17 g, a quantity of 107 moles of pure (pH 7) water, or 180 tonnes (18×107 g), contains close to 1 g of dissociated hydrogen ions (or rather 19 g of H3O+ hydronium ions) and 17 g of hydroxide ions.
Note that pH depends on temperature. For instance at 0°C the pH of pure water is 7.47. At 25°C it's 7.00, and at 100°C it's 6.14.
This definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. Ideally, electrode potential, E, follows the Nernst equation, which, for the hydrogen ion can be written as
E = E 0 + R T F ln  ( a H + ) = E 0 − 2.303 R T F p H {\displaystyle E=E^{0}+{\frac {RT}{F}}\ln(a_{{\textrm {H}}^{+}})=E^{0}-{\frac {2.303RT}{F}}\mathrm {pH} }
where E is a measured potential, E0 is the standard electrode potential, R is the gas constant, T is the temperature in kelvins, F is the Faraday constant. For H+ number of electrons transferred is one. It follows that electrode potential is proportional to pH when pH is defined in terms of activity. Precise measurement of pH is presented in International Standard ISO 31-8 as follows:[8] A galvanic cell is set up to measure the electromotive force (e.m.f.) between a reference electrode and an electrode sensitive to the hydrogen ion activity when they are both immersed in the same aqueous solution. The reference electrode may be a silver chloride electrode or a calomel electrode. The hydrogen-ion selective electrode is a standard hydrogen electrode.
Reference electrode | concentrated solution of KCl || test solution | H2 | Pt[clarification needed]
Firstly, the cell is filled with a solution of known hydrogen ion activity and the emf, ES, is measured. Then the emf, EX, of the same cell containing the solution of unknown pH is measured.
pH(X) = pH(S) + E S − E X z {\displaystyle {\text{pH(X)}}={\text{pH(S)}}+{\frac {E_{\text{S}}-E_{\text{X}}}{z}}}
The difference between the two measured emf values is proportional to pH. This method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/z is ideally equal to 1 2.303 R T / F {\displaystyle {\frac {1}{2.303RT/F}}\ } the "Nernstian slope".
To apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has an in-built reference electrode. It is calibrated against buffer solutions of known hydrogen ion activity. IUPAC has proposed the use of a set of buffer solutions of known H+ activity.[3] Two or more buffer solutions are used in order to accommodate the fact that the "slope" may differ slightly from ideal. To implement this approach to calibration, the electrode is first immersed in a standard solution and the reading on a pH meter is adjusted to be equal to the standard buffer's value. The reading from a second standard buffer solution is then adjusted, using the "slope" control, to be equal to the pH for that solution. Further details, are given in the IUPAC recommendations.[3] When more than two buffer solutions are used the electrode is calibrated by fitting observed pH values to a straight line with respect to standard buffer values. Commercial standard buffer solutions usually come with information on the value at 25 °C and a correction factor to be applied for other temperatures.
The pH scale is logarithmic and therefore pH is a dimensionless quantity.
p[H]
This was the original definition of Sørensen,[5] which was superseded in favor of pH in 1909. However, it is possible to measure the concentration of hydrogen ions directly, if the electrode is calibrated in terms of hydrogen ion concentrations. One way to do this, which has been used extensively, is to titrate a solution of known concentration of a strong acid with a solution of known concentration of strong alkaline in the presence of a relatively high concentration of background electrolyte. Since the concentrations of acid and alkaline are known, it is easy to calculate the concentration of hydrogen ions so that the measured potential can be correlated with concentrations. The calibration is usually carried out using a Gran plot.[9] The calibration yields a value for the standard electrode potential, E0, and a slope factor, f, so that the Nernst equation in the form
E = E 0 + f 2.303 R T F log  [ H + ] {\displaystyle E=E^{0}+f{\frac {2.303RT}{F}}\log[{\mbox{H}}^{+}]}
can be used to derive hydrogen ion concentrations from experimental measurements of E. The slope factor, f, is usually slightly less than one. A slope factor of less than 0.95 indicates that the electrode is not functioning correctly. The presence of background electrolyte ensures that the hydrogen ion activity coefficient is effectively constant during the titration. As it is constant, its value can be set to one by defining the standard state as being the solution containing the background electrolyte. Thus, the effect of using this procedure is to make activity equal to the numerical value of concentration.
The glass electrode (and other ion selective electrodes) should be calibrated in a medium similar to the one being investigated. For instance, if one wishes to measure the pH of a seawater sample, the electrode should be calibrated in a solution resembling seawater in its chemical composition, as detailed below.
The difference between p[H] and pH is quite small. It has been stated[10] that pH = p[H] + 0.04. It is common practice to use the term "pH" for both types of measurement.
pH indicators
Main article: pH indicator
Chart showing the variation of color of universal indicator paper with pH
Indicators may be used to measure pH, by making use of the fact that their color changes with pH. Visual comparison of the color of a test solution with a standard color chart provides a means to measure pH accurate to the nearest whole number. More precise measurements are possible if the color is measured spectrophotometrically, using a colorimeter or spectrophotometer. Universal indicator consists of a mixture of indicators such that there is a continuous color change from about pH 2 to pH 10. Universal indicator paper is made from absorbent paper that has been impregnated with universal indicator. Another method of measuring pH is using an electronic pH meter.
pOH
Relation between p[OH] and p[H] (red = acidic region, blue = basic region)
pOH is sometimes used as a measure of the concentration of hydroxide ions. OH−. pOH values are derived from pH measurements. The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by
[ O H − ] = K W [ H + ] {\displaystyle [\mathrm {OH} ^{-}]={\frac {K_{W}}{[\mathrm {H} ^{+}]}}}
where KW is the self-ionisation constant of water. Taking logarithms
p O H = p K W − p H {\displaystyle \mathrm {pOH} =\mathrm {pK_{W}} -\mathrm {pH} }
So, at room temperature, pOH ≈ 14 − pH. However this relationship is not strictly valid in other circumstances, such as in measurements of soil alkalinity.
Extremes of pH
Measurement of pH below about 2.5 (ca. 0.003 mol dm−3 acid) and above about 10.5 (ca. 0.0003 mol dm−3 alkaline) requires special procedures because, when using the glass electrode, the Nernst law breaks down under those conditions. Various factors contribute to this. It cannot be assumed that liquid junction potentials are independent of pH.[11] Also, extreme pH implies that the solution is concentrated, so electrode potentials are affected by ionic strength variation. At high pH the glass electrode may be affected by "alkaline error", because the electrode becomes sensitive to the concentration of cations such as Na+ and K+ in the solution.[12] Specially constructed electrodes are available which partly overcome these problems.
Runoff from mines or mine tailings can produce some very low pH values.[13]
Non-aqueous solutions
Hydrogen ion concentrations (activities) can be measured in non-aqueous solvents. pH values based on these measurements belong to a different scale from aqueous pH values, because activities relate to different standard states. Hydrogen ion activity, aH+, can be defined[14][15] as:
a H + = exp  ( μ H + − μ H + ⊖ R T ) {\displaystyle a_{H^{+}}=\exp \left({\frac {\mu _{H^{+}}-\mu _{H^{+}}^{\ominus }}{RT}}\right)}
where μH+ is the chemical potential of the hydrogen ion, μoH+ is its chemical potential in the chosen standard state, R is the gas constant and T is the thermodynamic temperature. Therefore, pH values on the different scales cannot be compared directly due to different solvated proton ions such as lyonium ions, requiring an intersolvent scale which involves the transfer activity coefficient of hydronium/lyonium ion.
pH is an example of an acidity function. Other acidity functions can be defined. For example, the Hammett acidity function, H0, has been developed in connection with superacids.
The concept of "Unified pH scale" has been developed on the basis of the absolute chemical potential of the proton. This scale applies to liquids, gases and even solids.[16]
Applications
pH values of some common substances
Pure water is neutral. When an acid is dissolved in water, the pH will be less than 7 (25°C). When a base, or alkali, is dissolved in water, the pH will be greater than 7. A solution of a strong acid, such as hydrochloric acid, at concentration 1 mol dm−3 has a pH of 0. A solution of a strong alkali, such as sodium hydroxide, at concentration 1 mol dm−3, has a pH of 14. Thus, measured pH values will lie mostly in the range 0 to 14, though negative pH values and values above 14 are entirely possible. Since pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration.
The pH of neutrality is not exactly 7 (25 °C), although this is a good approximation in most cases. Neutrality is defined as the condition where [H+] = [OH−] (or the activities are equal). Since self-ionization of water holds the product of these concentration [H+]×[OH−] = Kw, it can be seen that at neutrality [H+] = [OH−] =√(Kw), or pH = pKw/2. pKw is approximately 14 but depends on ionic strength and temperature, and so the pH of neutrality does also. Pure water and a solution of NaCl in pure water are both neutral, since dissociation of water produces equal numbers of both ions. However the pH of the neutral NaCl solution will be slightly different from that of neutral pure water because the hydrogen and hydroxide ions' activity is dependent on ionic strength, so Kw varies with ionic strength.
If pure water is exposed to air it becomes mildly acidic. This is because water absorbs carbon dioxide from the air, which is then slowly converted into bicarbonate and hydrogen ions (essentially creating carbonic acid).
CO 2 + H 2 O ↽ − − ⇀ HCO 3 − + H + {\displaystyle {\ce {{CO2}+{H2O}<=>{HCO3^{-}}+{H+}}}}
pH in soil
Classification of soil pH ranges
The United States Department of Agriculture Natural Resources Conservation Service, formerly Soil Conservation Service classifies soil pH ranges as follows: [17]
Denomination
pH range
Ultra acidic < 3.5
Extremely acidic 3.5–4.4
Very strongly acidic 4.5–5.0
Strongly acidic 5.1–5.5
Moderately acidic 5.6–6.0
Slightly acidic 6.1–6.5
Neutral 6.6–7.3
Slightly alkaline 7.4–7.8
Moderately alkaline 7.9–8.4
Strongly alkaline 8.5–9.0
Very strongly alkaline > 9.0
pH in nature
pH-dependent plant pigments that can be used as pH indicators occur in many plants, including hibiscus, red cabbage (anthocyanin) and red wine. The juice of citrus fruits is acidic mainly because it contains citric acid. Other carboxylic acids occur in many living systems. For example, lactic acid is produced by muscle activity. The state of protonation of phosphate derivatives, such as ATP, is pH-dependent. The functioning of the oxygen-transport enzyme hemoglobin is affected by pH in a process known as the Root effect.
Seawater
See also: Ocean acidification
The pH of seawater is typically limited to a range between 7.5 and 8.4.[18] It plays an important role in the ocean's carbon cycle, and there is evidence of ongoing ocean acidification caused by carbon dioxide emissions.[19] However, pH measurement is complicated by the chemical properties of seawater, and several distinct pH scales exist in chemical oceanography.[20]
As part of its operational definition of the pH scale, the IUPAC defines a series of buffer solutions across a range of pH values (often denoted with NBS or NIST designation). These solutions have a relatively low ionic strength (≈0.1) compared to that of seawater (≈0.7), and, as a consequence, are not recommended for use in characterizing the pH of seawater, since the ionic strength differences cause changes in electrode potential. To resolve this problem, an alternative series of buffers based on artificial seawater was developed.[21] This new series resolves the problem of ionic strength differences between samples and the buffers, and the new pH scale is referred to as the 'total scale', often denoted as pHT. The total scale was defined using a medium containing sulfate ions. These ions experience protonation, H+ + SO2−
4 ⇌ HSO−
4, such that the total scale includes the effect of both protons (free hydrogen ions) and hydrogen sulfate ions:
[H+]T = [H+]F + [HSO−
4]
An alternative scale, the 'free scale', often denoted 'pHF', omits this consideration and focuses solely on [H+]F, in principle making it a simpler representation of hydrogen ion concentration. Only [H+]T can be determined,[22] therefore [H+]F must be estimated using the [SO2−
4] and the stability constant of HSO−
4, K*
S:
[H+]F = [H+]T − [HSO−
4] = [H+]T ( 1 + [SO2−
4] / K*
S )−1
However, it is difficult to estimate K*
S in seawater, limiting the utility of the otherwise more straightforward free scale.
Another scale, known as the 'seawater scale', often denoted 'pHSWS', takes account of a further protonation relationship between hydrogen ions and fluoride ions, H+ + F− ⇌ HF. Resulting in the following expression for [H+]SWS:
[H+]SWS = [H+]F + [HSO−
4] + [HF]
However, the advantage of considering this additional complexity is dependent upon the abundance of fluoride in the medium. In seawater, for instance, sulfate ions occur at much greater concentrations (>400 times) than those of fluoride. As a consequence, for most practical purposes, the difference between the total and seawater scales is very small.
The following three equations summarise the three scales of pH:
pHF = − log [H+]F
pHT = − log ( [H+]F + [HSO−
4] ) = − log [H+]T
pHSWS = − log ( [H+]F + [HSO−
4] + [HF] ) = − log [H+]SWS
In practical terms, the three seawater pH scales differ in their values by up to 0.12 pH units, differences that are much larger than the accuracy of pH measurements typically required, in particular, in relation to the ocean's carbonate system.[20] Since it omits consideration of sulfate and fluoride ions, the free scale is significantly different from both the total and seawater scales. Because of the relative unimportance of the fluoride ion, the total and seawater scales differ only very slightly.
Living systems
pH in living systems[23]
Compartment
pH
Gastric acid 1.5-3.5[24]
Lysosomes 4.5
Human skin 4.7[25]
Granules of chromaffin cells 5.5
Urine 6.0
Cytosol 7.2
Blood (natural pH) 7.34–7.45
Cerebrospinal fluid (CSF) 7.5
Mitochondrial matrix 7.5
Pancreas secretions 8.1
The pH of different cellular compartments, body fluids, and organs is usually tightly regulated in a process called acid-base homeostasis. The most common disorder in acid-base homeostasis is acidosis, which means an acid overload in the body, generally defined by pH falling below 7.35. Alkalosis is the opposite condition, with blood pH being excessively high.
The pH of blood is usually slightly basic with a value of pH 7.365. This value is often referred to as physiological pH in biology and medicine. Plaque can create a local acidic environment that can result in tooth decay by demineralization. Enzymes and other proteins have an optimum pH range and can become inactivated or denatured outside this range.
Calculations of pH
The calculation of the pH of a solution containing acids and/or bases is an example of a chemical speciation calculation, that is, a mathematical procedure for calculating the concentrations of all chemical species that are present in the solution. The complexity of the procedure depends on the nature of the solution. For strong acids and bases no calculations are necessary except in extreme situations. The pH of a solution containing a weak acid requires the solution of a quadratic equation. The pH of a solution containing a weak base may require the solution of a cubic equation. The general case requires the solution of a set of non-linear simultaneous equations.
A complicating factor is that water itself is a weak acid and a weak base (see amphoterism). It dissociates according to the equilibrium
2 H 2 O ↽ − − ⇀ H 3 O + ( aq ) + OH − ( aq ) {\displaystyle {\ce {2H2O<=>{H3O+(aq)}+{OH^{-}(aq)}}}}
with a dissociation constant, Kw defined as
K w = [ H + ] [ OH − ] {\displaystyle K_{w}={\ce {[H+][OH^{-}]}}}
where [H+] stands for the concentration of the aqueous hydronium ion and [OH−] represents the concentration of the hydroxide ion. This equilibrium needs to be taken into account at high pH and when the solute concentration is extremely low.
Strong acids and bases
Strong acids and bases are compounds that, for practical purposes, are completely dissociated in water. Under normal circumstances this means that the concentration of hydrogen ions in acidic solution can be taken to be equal to the concentration of the acid. The pH is then equal to minus the logarithm of the concentration value. Hydrochloric acid (HCl) is an example of a strong acid. The pH of a 0.01M solution of HCl is equal to −log10(0.01), that is, pH = 2. Sodium hydroxide, NaOH, is an example of a strong base. The p[OH] value of a 0.01M solution of NaOH is equal to −log10(0.01), that is, p[OH] = 2. From the definition of p[OH] above, this means that the pH is equal to about 12. For solutions of sodium hydroxide at higher concentrations the self-ionization equilibrium must be taken into account.
Self-ionization must also be considered when concentrations are extremely low. Consider, for example, a solution of hydrochloric acid at a concentration of 5×10−8M. The simple procedure given above would suggest that it has a pH of 7.3. This is clearly wrong as an acid solution should have a pH of less than 7. Treating the system as a mixture of hydrochloric acid and the amphoteric substance water, a pH of 6.89 results.[26]
Weak acids and bases
A weak acid or the conjugate acid of a weak base can be treated using the same formalism.
Acid: HA ↽ − − ⇀ H + + A − {\displaystyle {\ce {HA<=>{H+}+{A^{-}}}}}
Base: HA + ↽ − − ⇀ H + + A {\displaystyle {\ce {HA+<=>{H+}+A}}}
First, an acid dissociation constant is defined as follows. Electrical charges are omitted from subsequent equations for the sake of generality
K a = [ H ] [ A ] [ HA ] {\displaystyle K_{a}={\frac {\ce {[H][A]}}{\ce {[HA]}}}}
and its value is assumed to have been determined by experiment. This being so, there are three unknown concentrations, [HA], [H+] and [A−] to determine by calculation. Two additional equations are needed. One way to provide them is to apply the law of mass conservation in terms of the two "reagents" H and A.
C A = [ A ] + [ HA ] {\displaystyle C_{\ce {A}}={\ce {[A]}}+{\ce {[HA]}}}
C H = [ H ] + [ HA ] {\displaystyle C_{\ce {H}}={\ce {[H]}}+{\ce {[HA]}}}
C stands for analytical concentration. In some texts one mass balance equation is replaced by an equation of charge balance. This is satisfactory for simple cases like this one, but is more difficult to apply to more complicated cases as those below. Together with the equation defining Ka, there are now three equations in three unknowns. When an acid is dissolved in water CA = CH = Ca, the concentration of the acid, so [A] = [H]. After some further algebraic manipulation an equation in the hydrogen ion concentration may be obtained.
[ H ] 2 + K a [ H ] − K a C a = 0 {\displaystyle [{\ce {H}}]^{2}+K_{a}[{\ce {H}}]-K_{a}C_{a}=0}
Solution of this quadratic equation gives the hydrogen ion concentration and hence p[H] or, more loosely, pH. This procedure is illustrated in an ICE table which can also be used to calculate the pH when some additional (strong) acid or alkaline has been added to the system, that is, when CA ≠ CH.
For example, what is the pH of a 0.01M solution of benzoic acid, pKa = 4.19?
Step 1: K a = 10 − 4.19 = 6.46 × 10 − 5 {\displaystyle K_{a}=10^{-4.19}=6.46\times 10^{-5}}
Step 2: Set up the quadratic equation. [ H ] 2 + 6 ⋅ 46 × 10 − 5 [ H ] − 6 ⋅ 46 × 10 − 7 = 0 {\displaystyle {\ce {{[H]^{2}}+{6.46\times 10^{-5}[H]}-6.46\times 10^{-7}=0}}}
Step 3: Solve the quadratic equation. [ H + ] = 7 ⋅ 74 × 10 − 4 {\displaystyle {\ce {{[H+]}=7.74\times 10^{-4}}}} ; pH = 3.11
For alkaline solutions an additional term is added to the mass-balance equation for hydrogen. Since addition of hydroxide reduces the hydrogen ion concentration, and the hydroxide ion concentration is constrained by the self-ionization equilibrium to be equal to K w [ H + ] {\displaystyle {\frac {K_{w}}{\ce {[H+]}}}}
C H = [ H ] + [ HA ] − K w [ H ] {\displaystyle C_{\ce {H}}={\frac {[{\ce {H}}]+[{\ce {HA}}]-K_{w}}{\ce {[H]}}}}
In this case the resulting equation in [H] is a cubic equation.
General method
Some systems, such as with polyprotic acids, are amenable to spreadsheet calculations.[27] With three or more reagents or when many complexes are formed with general formulae such as ApBqHr the following general method can be used to calculate the pH of a solution. For example, with three reagents, each equilibrium is characterized by an equilibrium constant, β.
[ A p B q H r ] = β p q r [ A ] p [ B ] q [ H ] r {\displaystyle [{\ce {A}}_{p}{\ce {B}}_{q}{\ce {H}}_{r}]=\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}}
Next, write down the mass-balance equations for each reagent:
C A = [ A ] + Σ p β p q r [ A ] p [ B ] q [ H ] r C B = [ B ] + Σ q β p q r [ A ] p [ B ] q [ H ] r C H = [ H ] + Σ r β p q r [ A ] p [ B ] q [ H ] r − K w [ H ] − 1 {\displaystyle {\begin{aligned}C_{\ce {A}}&=[{\ce {A}}]+\Sigma p\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}\\C_{\ce {B}}&=[{\ce {B}}]+\Sigma q\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}\\C_{\ce {H}}&=[{\ce {H}}]+\Sigma r\beta _{pqr}[{\ce {A}}]^{p}[{\ce {B}}]^{q}[{\ce {H}}]^{r}-K_{w}[{\ce {H}}]^{-1}\end{aligned}}}
Note that there are no approximations involved in these equations, except that each stability constant is defined as a quotient of concentrations, not activities. Much more complicated expressions are required if activities are to be used.
There are 3 non-linear simultaneous equations in the three unknowns, [A], [B] and [H]. Because the equations are non-linear, and because concentrations may range over many powers of 10, the solution of these equations is not straightforward. However, many computer programs are available which can be used to perform these calculations. There may be more than three reagents. The calculation of hydrogen ion concentrations, using this formalism, is a key element in the determination of equilibrium constants by potentiometric titration.
See also
Arterial blood gas
Chemical equilibrium
pCO2
Alkaline diet
References
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Jump up ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "activity (relative activity), a".
Jump up ^ International Union of Pure and Applied Chemistry (1993). Quantities, Units and Symbols in Physical Chemistry, 2nd edition, Oxford: Blackwell Science. ISBN 0-632-03583-8. pp. 49–50. Electronic version.
Jump up ^ Himmel, D.; Goll, S. K.; Leito, I.; Krossing, I. (2010). "A Unified pH Scale for all Phases". Angew. Chem. Int. Ed. 49 (38): 6885–6888. doi:10.1002/anie.201000252.
Jump up ^ Soil Survey Division Staff. "Soil survey manual.1993. Chapter 3, selected chemical properties.". Soil Conservation Service. U.S. Department of Agriculture Handbook 18. Retrieved 2011-03-12.
Jump up ^ Chester, Jickells, Roy, Tim (2012). Marine Geochemistry. Blackwell Publishing. ISBN 978-1-118-34907-6.
Jump up ^ Royal Society (2005). Ocean acidification due to increasing atmospheric carbon dioxide (PDF). ISBN 0-85403-617-2.
^ Jump up to: a b Zeebe, R. E. and Wolf-Gladrow, D. (2001) CO2 in seawater: equilibrium, kinetics, isotopes, Elsevier Science B.V., Amsterdam, Netherlands ISBN 0-444-50946-1
Jump up ^ Hansson, I. (1973). "A new set of pH-scales and standard buffers for seawater". Deep-Sea Research. 20 (5): 479–491. Bibcode:1973DSROA..20..479H. doi:10.1016/0011-7471(73)90101-0.
Jump up ^ Dickson, A. G. (1984). "pH scales and proton-transfer reactions in saline media such as sea water". Geochim. Cosmochim. Acta. 48 (11): 2299–2308. Bibcode:1984GeCoA..48.2299D. doi:10.1016/0016-7037(84)90225-4.
Jump up ^ Boron, Walter, F.; Boulpaep, E.L. (2004). Medical Physiology: A Cellular And Molecular Approach. Elsevier/Saunders. ISBN 1-4160-2328-3.
Jump up ^ Marieb EN, Hoehn K (2010). Human anatomy & physiology. San Francisco: Benjamin Cummings. ISBN 0-8053-9591-1.
Jump up ^ Lambers, H.; Piessens, S.; Bloem, A.; Pronk, H.; Finkel, P. (2006-10-01). "Natural skin surface pH is on average below 5, which is beneficial for its resident flora". International Journal of Cosmetic Science. 28 (5): 359–370. ISSN 1468-2494. PMID 18489300. doi:10.1111/j.1467-2494.2006.00344.x.
Jump up ^ Maloney, Chris. "pH calculation of a very small concentration of a strong acid.". Retrieved 13 March 2011.
Jump up ^ Billo, E.J. (2011). EXCEL for Chemists (3rd ed.). Wiley-VCH. ISBN 978-0-470-38123-6.
External links
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The pH Scale
Chem1 Virtual Textbook, Acid-base Equilibria and Calculations
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Food and Foodstuff – pH Values
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values: \mathrm {pOH} =\mathrm {pK_{W}} -\mathrm {pH}

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values: {\displaystyle K_{a}={\frac {\ce {[H][A]}}{\ce {[HA]}}}}

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values: {\displaystyle {\frac {K_{w}}{\ce {[H+]}}}}

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https://af.wikipedia.org/wiki/PH
PH – Afrikaans
af
af
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https://als.wikipedia.org/wiki/PH-Wert
PH-Wert – Alemannisch
als
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interlanguage-link-target

values: أس هيدروجيني – Arabic

values: Вадародны паказчык – Belarusian

values: Водороден показател – Bulgarian

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https://bs.wikipedia.org/wiki/PH
PH – Bosnian
bs
bs
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https://ca.wikipedia.org/wiki/PH
PH – Catalan
ca
ca
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https://cs.wikipedia.org/wiki/PH
PH – Czech
cs
cs
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https://cy.wikipedia.org/wiki/PH
PH – Welsh
cy
cy
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https://da.wikipedia.org/wiki/PH
PH – Danish
da
da
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https://de.wikipedia.org/wiki/PH-Wert
PH-Wert – German
de
de
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https://el.wikipedia.org/wiki/PH
PH – Greek
el
el
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https://es.wikipedia.org/wiki/PH
PH – Spanish
es
es
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https://eu.wikipedia.org/wiki/PH
PH – Basque
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eu
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PH – Irish
ga
ga
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https://gl.wikipedia.org/wiki/PH
PH – Galician
gl
gl
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https://hak.wikipedia.org/wiki/PH
PH – Hakka Chinese
hak
hak
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values: 수소 이온 농도 – Korean

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PH – Hindi
hi
hi
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PH – Croatian
hr
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PH – Ido
io
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https://id.wikipedia.org/wiki/PH
PH – Indonesian
id
id
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PH – Italian
it
it
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PH – Hebrew
he
he
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values: ಪಿ ಹೆಚ್ – Kannada

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https://pam.wikipedia.org/wiki/PH
PH – Pampanga
pam
pam
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https://kk.wikipedia.org/wiki/PH
PH – Kazakh
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https://ht.wikipedia.org/wiki/PH
PH – Haitian Creole
ht
ht
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https://ku.wikipedia.org/wiki/Nirxa_pH
Nirxa pH – Kurdish
ku
ku
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PH – Latvian
lv
lv
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PH – Hungarian
hu
hu
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values: Водороден показател – Macedonian

values: പി.എച്ച്. മൂല്യം – Malayalam

values: पी.एच. मूल्य – Marathi

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https://ms.wikipedia.org/wiki/PH
PH – Malay
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PH – Burmese
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PH – Dutch
nl
nl
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values: 水素イオン指数 – Japanese

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PH – Norwegian
no
no
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PH – Norwegian Nynorsk
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PH – Novial
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PH – Occitan
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PH – Uzbek
uz
uz
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PH-Weert – Low German
nds
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https://pl.wikipedia.org/wiki/Skala_pH
Skala pH – Polish
pl
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PH – Portuguese
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PH – Romanian
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PH – Scots
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https://sq.wikipedia.org/wiki/PH
PH – Albanian
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PH – Sicilian
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PH – Simple English
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simple
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PH – Slovenian
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sl
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https://so.wikipedia.org/wiki/PH
PH – Somali
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values: PH вредност – Serbian

values:
https://su.wikipedia.org/wiki/PH
PH – Sundanese
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su
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Happamuus – Finnish
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fi
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PH – Swedish
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PH – Tagalog
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tl
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values: காரகாடித்தன்மைச் சுட்டெண் – Tamil

values:
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PH – Telugu
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PH – Turkish
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PH – Ukrainian
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PH – Vietnamese
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PH – West Flemish
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PH – Waray
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text:
Aleutian Trench
From Wikipedia, the free encyclopedia
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Map of the Aleutian Trench
The Aleutian Trench (or Aleutian Trough)[1] is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for 3,400 km from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific Plate is being subducted under the North American Plate at a dip angle of nearly 45°. The rate of closure is 3 inches (76 mm) per year.[2]
Contents
[hide]
1 Trench morphology
2 Associated seismicity
3 References
4 External links
Trench morphology[edit]
The north side of the trench slopes 3°–4° and the south side 1°–4°.[3] The deepest part of the Aleutian trench has been measured at 7,822 metres (25,663 ft) at 51.21°N, 174.83°E.,[4] located about 145 km SSW of Buldir Island.
Center pressure: 10,762 pounds per square inch (732.3 atm; 74.20 MPa).[5] Variations in total magnetic intensity (residual) of more than 600 γ (600 nanoteslas) were found in the center of the trench and more than 1100 γ on the southern flank.[6]
Associated seismicity[edit]
The subduction of the Pacific Plate below the North American Plate along the Aleutian Trench is associated with numerous earthquakes. Several of these earthquakes are notable for their size and/or associated tsunamis.
April 1, 1946 Aleutian Islands earthquake: This magnitude 8.1 earthquake occurred offshore Unimak Island,[7] and caused only minor damage on land. However, the shaking generated a tsunami which killed 5 on the island and caused damage on other Aleutian Islands and North and South America. In Hilo, Hawaii, the tsunami killed 159 and caused extensive damage.
March 9, 1957 Andreanof Islands earthquake: This magnitude 8.6[8] earthquake occurred south of the Andreanof Islands. The earthquake itself caused damage on Adak Island and Umnak Island and generated a Pacific-wide tsunami. The tsunami caused extensive damage in Scotch Cap on Unimak Island, including the destruction of the Scotch Cap Light, and destroyed two villages in the Hawaiian Islands. The tsunami was recorded as far away as Chile.[9]
February 4 1965 Rat Islands earthquake: This magnitude 8.7 earthquake triggered a tsunami that struck Shemya Island and was observed around the Pacific, but caused little damage.
May 7, 1986 Andreanof Islands earthquake: This magnitude 7.9 earthquake caused damage on Adak Island and Atka Island. The resultant tsunami was recorded throughout the Pacific.[10]
On June 23, 2014, a 7.9 quake occurred near Little Sitkin Island, Alaska.
On July 17, 2017, a magnitude 7.7 quake occurred 198 km ESE of Nikol'skoye Russia.[11]
References[edit]
Jump up ^ Webster's New Geographical Dictionary. Springfield, Massachusetts: Merriam-Webster Inc. 1984. p. 30. ISBN 0-87779-446-4.
Jump up ^ "Aleutian Trench". Archived from the original on February 25, 2014. Retrieved May 4, 2012.
Jump up ^ "Profile of Aleutian Trench". Retrieved May 6, 2012.
Jump up ^ "North Pacific Ocean Bering Sea (Southern Part)". NOAA Chart 513 7th Edition. June 2004. Retrieved 29 November 2012.
Jump up ^ "Aleutian Trench Data". Archived from the original on February 9, 2013. Retrieved May 6, 2012.
Jump up ^ "Magnetic Information". Retrieved May 6, 2012.
Jump up ^ USGS - Historic Earthquakes, Unimak Island Archived 2013-07-31 at the Wayback Machine.
Jump up ^ USGS - Historic Earthquakes, 1957 Andreanof Islands
Jump up ^ USC Tsunami Research Group
Jump up ^ USGS - Historic Earthquakes
Jump up ^ "M 7.7 - 198km ESE of Nikol'skoye, Russia". earthquake.usgs.gov. Retrieved 2017-07-18.
External links[edit]
A New Perspective on Seismic Hazards in the Shumagin Gap – Alaska Earthquake Center
Coordinates: 52°N 172°E / 52°N 172°E / 52; 172
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BrainPop
From Wikipedia, the free encyclopedia
Jump to: navigation, search
BrainPop
Type
Curriculum based websites
Founded
December 31, 1999; 17 years ago (1999-12-31)[1]
Founder
Avraham Kadar, M.D.
Products
BrainPop, BrainPop Jr., BrainPop UK, BrainPop ESL, BrainPop Educators, My BrainPop, Brainpop Espanol, among other languages
Website
www.brainpop.com
BrainPop (styled BrainPOP) is a group of educational websites with over 1,000[2] short animated movies for students in grades K-12 (ages 6 to 17), together with quizzes and related materials, covering the subjects of science, social studies, English, mathematics, engineering and technology, health, and arts and music. BrainPop is used in more than 20% of U.S. schools and also offers subscriptions for families and homeschoolers.[3] It is also used in schools in Mexico, the UK, France, Spain, Israel and several other countries, where it offers videos in local languages that are designed for students in those countries. BrainPop is available by subscription but has some free content, including a movie of the day, several free movies from each topic area, educators materials, including lesson plans, and an extensive library of educational games called GameUp. Its free smartphone and tablet application accesses BrainPop's free and subscription content.
The videos and other materials are designed to engage students and assist teachers and home schoolers; they are aligned to state education standards. Most of the videos feature the characters Tim and Moby.[4] In addition to BrainPop.com for older children, there is BrainPop Jr. for younger children (grades K-3), BrainPop Español, BrainPop Français, BrainPop UK, BrainPop ESL for non-native speakers learning English, BrainPop Educators, a free site for teachers and parents to post materials and interact with BrainPop and each other, GameUp and My BrainPop, a tool for students and teachers to record learning accomplishments. The sites are owned by FWD Media, Inc. and its affiliates, based in New York.
Contents
[hide]
1 Description of the site
1.1 History and products
1.2 Reputation
2 BrainPop characters
2.1 Tim
2.2 Moby
2.3 Other characters
3 BrainPop Jr.
3.1 Characters in BrainPop Jr.
4 BrainPop Educators and BrainPop ESL
5 GameUp
6 See also
7 References
8 External links
Description of the site[edit]
History and products[edit]
Founded in 1999,[1] the BrainPop websites display animated, curriculum-based content that supports educators and are intended to be fun and motivational for students to watch.[5][6] The sites' movies cover the subjects of science, social studies, English, mathematics, engineering & technology, health, and arts and music. Since 2007, the movies have been closed captioned. The sites also access a wide variety of educational games. BrainPop is used in more than 25% of U.S. schools[3] and in many schools outside the U.S., as well as by parents, homeschoolers and others.[7] The company was founded by Avraham Kadar, M.D., an immunologist and pediatrician, to explain medical concepts to his young patients using animation.[8][9] As of 2011, BrainPop hosted more than 11 million unique visits each month, from thousands of schools and individuals worldwide.[9] BrainPop uses an in-house team of educators, animators and writers to produce and continually update the sites, incorporating teacher and parent input.[8][10]
The site's resources include BrainPop.com, for grades 3 and up (over age 9) and BrainPop Jr., for grades K-3 (ages 5 to 9). The sites also offer movies in three different languages for regional markets: BrainPop Español for Spanish-speakers, BrainPop Francais (French) and BrainPop UK (English with UK-centered topics) aligned to local educational standards.[11][12] The site's free, interactive resource for teachers and homeschoolers, BrainPop Educators, features free tips, tools and best practices by and for educators.[13] My BrainPop is a tool for students and teachers to record learning accomplishments, and teachers can track students' progress.[12] In 2009, BrainPop introduced BrainPop ESL, targeted at students learning English as a second language. Schools and parents can use the site to help shape the student's curriculum.[8] BrainPop's free GameUp website contains free online games from third-party game publishers that coordinate with the BrainPop, BrainPop Jr. and BrainPop ESL curricula.[14]
BrainPop movies may be used to introduce a new lesson or topic, for illustrating complex subject matter or to review before a test. Content is aligned to USA state education standards and is searchable by topic or state standard.[10][12] In addition to movies, the site displays quizzes, educational games, experiments and other related content that students can use interactively to reinforce the lessons in the movies.[15][16] BrainPop products are compatible with PCs, Macs, projectors and interactive whiteboards, as well as applications for tablets and smart phones. No downloading, installation or special hardware is required.[17] The movies feature recurring characters such as the robot Moby, Tim (a teenager, at BrainPop) and Annie (a younger girl, at BrainPop Jr.).[8] Most of the movies begin with the characters responding to correspondence and end humorously, often with Tim getting annoyed at Moby or vice versa.
Reputation[edit]
"BrainPOP has built a reputation for quality, thoughtfulness, and robust support for teachers".[7] BrainPop and its products have earned numerous awards and recognition from Common Sense Media, the CODiE Awards, Association of Educational Publishers, District Administration magazine, Forbes magazine, Association for Library Service to Children, Association of Educational Publishers, Digital Innovation in Learning Awards, Tech & Learning Magazine, the KAPi Awards, Apps for Homeschooling, International Serious Play Awards, Learning Magazine, EdNet's Best, Teacher's Choice Awards, eSchool News, Homeschool.com, Apple Education, the Interactive Media Awards, Teachers With Apps and Distinguished Achievement Awards, Media & Methods.[18][19] A 2009 multi-grade study by SEG research, entitled "A Study of the Effectiveness of BrainPop", involved over 1,000 students in schools in Palm Beach County, Florida and New York City. The BrainPop-financed study concluded, "Students in classes using BrainPop made significant improvements compared to students in classes not using BrainPop."[20][21]
Reviews for the websites and movies have been favorable. A review in Common Sense Media commented: "BrainPOP is a standard-bearer for quality, self-directed online educational content. … A year's subscription is worth it because there's at least a year's worth of content for a kid to explore on BrainPOP."[22] A home schooler wrote in Curriculum Choice: "The videos are very funny, plus they explain information in a way that is easy for kids to understand and remember. … [The quizzes are] a quick and easy way for me to see whether [the students] really grasped the material."[23] A review in The Reading Matrix stated:
These presentations provide meaningful, standard-driven instruction and assessment [due] to the exceptional quality. … One of the best features that teachers like about BrainPop is its ease of use. … [T]he layout, webinars, and free tutorials make navigating through the tremendous amount of information a cinch. … [A] State Standards Tool … allows educators to search their state standards in order to fit different activities with appropriate standards. … [The] interactive characters … help explain concepts, design experiments, and show students how to acquire a particular skill or use the information given. … Tim and Moby have personalities of their own and are relatable, trustworthy friends to their viewers. … [the] site allows students to teach themselves.[24]
Schools recommend the product.[25] A teacher wrote to eSchool News, "This product has made my students excited to take the quiz after the video. How many teachers can say that about their students?"[19] Praising a BrainPop video about Ada Lovelace, Wired magazine wrote, "After reading more about her life and her work, I still feel it is best summarized by BrainPop’s Ada Lovelace video, which is designed for kids."[26] Another reviewer felt that a good feature of BrainPop's movies is their brevity: "just enough to capture and engage children."[27][28] After budgetary cuts caused the cancellation of a Michigan school's subscription to BrainPop in 2014, teachers raised money from students to bring it back in 2015.[29]
The educational site connexions.org wrote: "I recommend this site to teachers who want to inform and entertain their students. The videos are a unique educational tool with loveable [sic] characters. … BrainPop will not only enliven the classroom, but the site is dependable with lessons following state and grade-level standards."[30][31] Teach Magazine noted, "Tim and Moby … illustrate often difficult concepts in a fun format uniquely suited for the 21st-century learner."[32] In 2011, Canada's TEACH Magazine wrote that the movies are presented "in a fun format uniquely suited for the 21st-century learner. … BrainPop movies are ideal for both group and one-on-one settings and can be used to introduce new lessons or topics or to illustrate complex themes as review before a test.[16] In 2015, Yahoo! Tech selected BrainPop for its list of "Eleven Great Digital Homework Helpers for Your Kids",[33] and SheKnows Media listed it among its top educational sites for kids.[34]
In 2010, The New York Times wrote of the company's free smartphone and tablet application: "BrainPop is a worthy app, featuring a new brief educational cartoon every day. The cartoon is followed by a quick quiz that will at times challenge even a grown-up."[35] The Epoch Times featured the application as its "iPhone App of the Week" and called the movies "usually funny, if somewhat corny, and always engaging".[36] The Explore Knowledge Academy, the first public charter i-school in Nevada, has recommended BrainPop's phone and tablet application,[37] as has ChanelproSMB,[38] Family Circle,[39] Common Sense Media[40] Cool Mom Tech[41] and The Educator's Room.[42] ADDitude Magazine selected the app as one of three apps to "sharpen reading skills".[43]
BrainPop characters[edit]
Tim and Moby are the main characters in most BrainPop movies.[12]
Tim[edit]
Tim is a teenager who does most of the talking in the movies and understands what Moby says. The design on his shirt usually matches the topic being covered. At the beginning of each video, Tim reads a letter from a student asking about the topic.[44] Often at the end of the movies, Moby will humorously annoy Tim, or vice versa.[45]
Moby[edit]
Moby the Robot is an orange robot who communicates in beeping noises. The three lights on his chest light up when he beeps, and Tim usually translates what he's saying. Moby is Tim's friend but loves to drive him crazy. Moby helps out by fetching things for Tim and asking questions about the topic they are discussing. As a robot, he can do things that people are unable to do, such as changing his hand into a freeze-ray, sending himself back in time, throwing garbage into a black hole in space, removing his head, and using lasers. Some of the movies, such as the Earth, Radar and Milky Way videos, imply that Moby is of an extraterrestrial origin. However, the Leonardo da Vinci movie implies that he was invented by da Vinci.[45]
Other characters[edit]
Cassie and Rita are two teenage girls, who are best friends and are mainly featured in comics that accompany many of the movies in the "FYI" section. They also occasionally appear in the main movies and even narrate a few of them. Rita tends to be more composed and intelligent, while Cassie tends to be more absent-minded. Like Moby, Cassie enjoys annoying Tim, while some of the movies imply that Rita has a romantic interest in Tim and that he returns her feelings.
Bob is a rat with a broken tail and a patched chest. He is featured in, and often conducts, experiments called "Experiments with Bob the Ex-Lab Rat", which relate to mostly science movies.[44]
Gary and gary are a father and son featured in comics called "How To With Gary and gary", which show how to do something safely. The capitalized "Gary" is the father, and the lowercase "gary" is the son.
BrainPop Jr.[edit]
BrainPop Jr. was launched in 2006.[46] It is similar to BrainPop in subject areas, but the movies are geared towards grades K-3 (age 5-9). The hosts are Moby and a little girl named Annie.[12] Like the regular BrainPop, the site offers a free "Movie of the Week", as well as several free movies in the different curricular areas.[47] Common Sense Media wrote called "BrainPop Jr. "a high-quality educational site that kids can navigate easily on their own. This interactive site includes videos, audio prompts, and graphics familiar to kids in an ideal format for young learners. Kids can take their enjoyment of videos to the next, more effective, level and do something with what they've just watched online … [and explore] sub-categories, like the science and math sections. If your K-3 child likes to learn things online, this site is worth the subscription fee."[48] Common Sense Media also praised the free movies' video quality and topic variety, and writing, "The videos cover a lot of ground but are easy to follow and fun to watch; they'll explain things slowly and deliberately and at a level that's appropriate for young elementary school kids [but] it will be largely up to parents to get kids engaged in further exploration of the material."[49]
Characters in BrainPop Jr.[edit]
Annie is a young girl who narrates the movies. She wears red framed glasses and also works with Moby. She has a teenaged sister named Mia. There are many hints in BrainPop Jr. that Annie is Mexican. For instance, her dog's name is Señor Maurice, and she sometimes refers to her father as "Papi".
In BrainPop Jr., Moby shows his emotions more often, like crying or getting excited. Moby is more kind-hearted in BrainPop Jr. than in BrainPop. He can also do things the other Moby can't do, like sneeze, sweat, and drink things, like water. He can also be sick and smell flowers.
Frank and Joey are two fish that star in the comic strip "Belly Up."
BrainPop Educators and BrainPop ESL[edit]
BrainPop Educators was introduced in 2008.[50] It is an online community of 125,000 teachers,[51] and parents who use BrainPop. This free site offers answer keys to activity pages, graphic organizers, professional development materials, posters, clipart and other resources for educators.[12][16] It also allows educators to collaborate and share resources, such as lesson plans, organizers and activities for students. The site also offers video tutorials and webinars.[10][13] My BrainPop, added in 2013, is a tool for students and teachers to record learning accomplishments from game play, activities, quizzes and other content.[52]
BrainPop ESL (English as a second language) is a website launched in 2009[53] that displays animated videos providing grammar and vocabulary instruction and interactive exercises for non-native English speakers of all ages. Each video contains an animated story, an introduction to new vocabulary, and an illustration of relevant grammar topics. The narrator is a boy named Ben, who is accompanied by Moby the robot.[12] The videos provide a series of increasingly challenging contextualized language and content exercises for English learners, starting with beginner levels and progressing to advanced levels.[54] Students may select review activities, such as “Words, Words, Words”, a vocabulary exercise that uses flashcards and includes a pronunciation guide; "Hear it, Say it", to reinforce vocabulary and speaking; "Read it", for reading comprehension; and "Write it", for writing practice. There are also games and quizzes to review ideas from the videos.[55] Internet-based websites have been shown to be useful tools to supplement in-class instruction for ESL students.[56] Education Week recommends BrainPop ESL, writing that it "helps build background knowledge and concrete visual examples."[57]
GameUp[edit]
In 2011, BrainPop launched its educational games site, GameUp, which contains a collection of free online games from third-party game publishers and BrainPop's designers that help teach a variety of subjects and coordinate with the BrainPop, BrainPop Junior and BrainPop ESL curricula.[7][58][59] BrainPop partners with developer organizations and community developers to continually expand and improve the site's content and align the games with academic standards.[9] More than 100 games were featured on the site by 2014[23] based on the Common Core State Standards Initiative.[60] GameUp aims to help teachers use educational games in the classroom to engage and motivate students. It is supported by BrainPop Educators.[14][58]
New Media Consortium wrote: "GameUp features top online educational gaming titles as well as support and supplementary materials to educators. GameUp titles come from an impressive collection of organizations such as Nobelprize.org®, iCivics, JASON Project, Mangahigh, and National Council of Teachers of Mathematics, to name a few."[14] Edutopia, Education Week and The Wall Street Journal are among other sources that recommend GameUp.[61][62][63] BrainPop "curates their games very carefully and considers a wide range of factors, from a game's curricular value to the length of experience appropriate for classroom use, and thoughtfully pairs games with supplemental lessons and materials that allow teachers to quickly and easily integrate the games into their classrooms."[7]
See also[edit]
Comparison of educational websites that are directed to persons 17 or under
References[edit]
^ Jump up to: a b The Certificate of Incorporation of Brainpop.com, LLC was filed with the Secretary of State of the State of Delaware on December 31, 1999. Search Brainpop.com, LLC, Department of State: Division of Corporations, State of Delaware, accessed March 29, 2016
Jump up ^ "Hilldale Elementary School receives technology grant"[permanent dead link], NorthJersey.com, January 20, 2012
^ Jump up to: a b "Free Animated Movies for Black History Month" Archived January 11, 2010, at the Wayback Machine.. Newsday, February 4, 2007
Jump up ^ "Seen on Saturday – September 29th, 2007". ABC News, September 27, 2007
Jump up ^ BrainPop profile at Education World, August 2006
Jump up ^ Web Resources. Columbia University Teachers College. Retrieved March 3, 2010.
^ Jump up to: a b c d Richards, Anne. "Why You Should Be Paying Attention to BrainPOP", Kidscreen.com, October 6, 2014
^ Jump up to: a b c d Seltzer, Sarah. "'Pop' Movies that Educate", New York Family magazine, May 2007, pp. 108–09. Retrieved March 3, 2010.
^ Jump up to: a b c BrainPop: About Us. Retrieved 17 February 2010.
^ Jump up to: a b c "Interview with BrainPop's Allisyn Levy". Teachhub.com. Retrieved March 3, 2010.
Jump up ^ BrainPop profile Archived February 3, 2009, at the Wayback Machine. at Web100.com
^ Jump up to: a b c d e f g "BrainPop", Edsurge, accessed December 23, 2014
^ Jump up to: a b "BrainPop Educators: A New Resource With Free Tips, Tools & Ideas". Ed Tech Show Daily, January 22, 2009. Retrieved March 3, 2010.
^ Jump up to: a b c Estrada, Victoria. "GameUp with BrainPop", New Media Consortium, August 3, 2012
Jump up ^ "BrainPop Turns Dads Into Geniuses" Archived February 7, 2009, at the Wayback Machine., Rare Bird Articles, August 18, 2003
^ Jump up to: a b c "BrainPop". TEACH Magazine, January 24, 2011
Jump up ^ Dawson, Carolyn J. "Apple iPad Gets Free Educational App from BrainPop". TMCnet, April 6, 2010, accessed August 20, 2010; Smart, Gavin. "Students learning independently using the BrainPOP UK App", Smarter Learning, November 2, 2012; BrainPop Tour
Jump up ^ BrainPop's Awards page
^ Jump up to: a b "Our readers’ top ed-tech picks for 2012", eSchool News, January 3, 2012
Jump up ^ "A Study of the Effectiveness of BrainPop". SEG Research, 2009. Retrieved August 20, 2010.
Jump up ^ See also Rosen, Yigal (Faculty of Education, University of Haifa). (2009). "The effects of an animation-based on-line learning environment on transfer of knowledge and on motivation for science and technology learning", Journal of Educational Computing Research, Vol. 40(4) pp. 451–467 doi:10.2190/EC.40.4.d
Jump up ^ Villamagna, Dana. "BrainPop" (Section: Is it any good?), Common Sense Media, November 13, 2012; Villamagna, Dana. "BrainPop, Jr.", Common Sense Media, August 30, 2012
^ Jump up to: a b Zechman, Megan. "BrainPOP Review", Curriculum Choice, October 13, 2014
Jump up ^ Nichter, Nicole, BrainPop review. The Reading Matrix, Volume 10, Number 1, April 2010
Jump up ^ "BrainPop offers learning opportunities at school and at home" Archived June 10, 2015, at the Wayback Machine., Dawes Middle School, Lincoln, Nebraska, accessed February 10, 2012
Jump up ^ Williams, Jenny. "Ada Lovelace Day: Celebrate Women in Technology". Wired magazine, March 24, 2010. Retrieved August 20, 2010.
Jump up ^ Bray, Oliver. "BrainPop UK: Fantastic, Engaging Flash Animation Videos for your Classroom". Olliebray.com, January 6, 2009. Retrieved August 20, 2010.
Jump up ^ Fukunaga, Yuji. "How Do You Explain Autism to Your Son?" Archived February 11, 2012, at the Wayback Machine., Winnetka-Glencoe Patch, January 17, 2012
Jump up ^ Koury, Mike. "Handley elementary staff kiss a pig to raise money for school program", mLive.com, December 20, 2014
Jump up ^ Bartlett, Emily. "BrainPop in a secondary classroom". Connexions.org, October 29, 2009 accessed August 20, 2010
Jump up ^ See also this 2009 review and following comments at the Educational Technology Weblog.
Jump up ^ "BrainPop". Teach Magazine, January 24, 2011
Jump up ^ Tynan-Wood, Christina. "Eleven Great Digital Homework Helpers for Your Kids", July 22, 2015
Jump up ^ Robbins, Jill. "If your kid's going to have screen time, at least make it worthwhile", SheKnows Media, December 17, 2015
Jump up ^ Tedeschi, Bob. "Top Picks for Apps to Help You While Away the Minutes". The New York Times, December 22, 2010
Jump up ^ "iPhone App of the Week: BrainPop". The Epoch Times, 28 June–4 July 2011, p. A8
Jump up ^ "10 educational iPad apps recommended by Explore Knowledge Academy", eSchool News, February 22, 2012
Jump up ^ "25 Best Education Apps for K-12 Classrooms: iOS and Android", ChannelproSMB, 2013, accessed January 15, 2014
Jump up ^ "Best Educational Apps for Tweens and Teens", Family Circle, 2013, accessed January 15, 2014
Jump up ^ "Teacher Review for BrainPOP Featured Movie", Common Sense Media, October 28, 2013
Jump up ^ Refford, Christina. "Brain Pop Featured Movie: Our cool free app of the week", Cool Mom Tech, March 27, 2016
Jump up ^ Winchester, Sarah. "APP-itudes: The Apps You Need in Every Classroom", The Educator's Room, June 5, 2014
Jump up ^ Kulman, Randy. "3 Apps to Sharpen Reading Skills", accessed February 1, 2016
^ Jump up to: a b "Ways to Use BrainPop at Home", Brainpop, 2007, accessed March 31, 2012
^ Jump up to: a b Brainpop movies and profiles of Tim and Moby at Sparktop.org
Jump up ^ Jarrett, Kevin. "BrainPop Jr. has launched!" Archived March 27, 2012, at the Wayback Machine. September 5, 2006, accessed July 27, 2011
Jump up ^ Maple, Sandy. "ParentDish's 27 Top Web Sites for Kids". Parentdish, February 27, 2010
Jump up ^ Villamagna, Dana. "BrainPop Jr." (click on "Is it any good?), Common Sense Media, 2011, accessed October 22, 2014
Jump up ^ VanderBorght, Mieke. "BrainPOP Jr. Movie of the Week", Common Sense Media, 2014
Jump up ^ "BrainPop Introduces BrainPop Educators" Archived September 30, 2011, at the Wayback Machine.. BrainPop press release, September 17, 2008, accessed July 27, 2011
Jump up ^ Joseph, Dawn. "Get Involved in the National STEM Video Game Challenge Today!" White House Office of Science and Technology Policy, December 20, 2010
Jump up ^ "My BrainPop FAQ", Brainpop.com, accessed January 15, 2014
Jump up ^ "BrainPop Announces Launch of English as a Second Language Program, BrainPop ESL". BrainPop press release, September 8, 2009, accessed July 27, 2011
Jump up ^ About Us. BrainPop.com. Retrieved March 15, 2010.
Jump up ^ Kim, Yunjin (June 2011). "BrainPop ESL". The Electronic Journal for English as a Second Language. 15 (1). Retrieved 30 June 2011.
Jump up ^ Kung, Shiao-Chuan; Tun-Whei Chuo (June 2002). "Students' Perceptions of English Learning Through ESL/EFL Websites". The Electronic Journal for English as a Second Language. 6 (1).
Jump up ^ Davis, Michelle R. "Schools Face Shortage of Digital Curricula for English-Learners", Education Week, May 20, 2013, published in print as "English-Learners Going Digital", May 22, 2013
^ Jump up to: a b "New! GameUp Top Offerings from Leading Educational Games Publishers", BrainPop.com, June 26, 2011, accessed April 19, 2012
Jump up ^ Miller, Andrew. "Free Tools to Incorporate Game-Based Learning", Edutopia, February 20, 2013
Jump up ^ "Game Based Learning with BrainPop’s GameUp", Eduspire.org, accessed September 21, 2015
Jump up ^ Miller, Andrew. "Free Tools to Incorporate Game-Based Learning", Edutopia, February 20, 2013
Jump up ^ Molnar, Michele and Sean Cavanagh. "Consumer Demand for Digital Learning Games, Simulations Growing Worldwide", Education Week, September 17, 2013
Jump up ^ Shellenbarger, Sue. "New Approaches to Teaching Fractions", The Wall Street Journal, September 24, 2013
External links[edit]
Official website
BrainPop UK official site
BrainPop Israel official site
Video of a teacher using BrainPop, from Education Week (2013)
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