For what does the letter H stand in the pH scale?
"reactions occur in the soil that make aluminium available to these plants, turning the flowers blue. In alkaline soils, these reactions cannot occur and therefore aluminium is not taken up by the plant. As a result, the flowers remain pink. PH indicator A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually. Hence, a pH indicator is a chemical detector for hydronium ions (HO) or hydrogen ions (H) in the Arrhenius model. Normally, the indicator causes the color of the solution to"
"S are listed in Definitions of pH scales, standard reference values, measurement of pH, and related terminology. Pure Appl. Chem. (1985), 57, pp 531–542, where further details can be found. pH has no fundamental meaning; its official definition is a practical one. However, in the restricted range of dilute aqueous solutions having amount-of-substance concentrations less than 0.1 mol/L, and being neither strongly alkaline nor strongly acidic (2 < pH < 12), the definition is such that where ""c""(H) denotes the amount-of-substance concentration of hydrogen ion H and ""y"" denotes the activity coefficient of a typical uni-univalent electrolyte in the solution."
"acid species is the hydrated hydrogen ion HO (or more accurately [H(OH)]). In this case ""H"" and ""H"" are equivalent to pH values determined by the buffer equation or Henderson-Hasselbalch equation.<br> However, an ""H"" value of −21 (a 25% solution of SbF in HSOF) does not imply a hydrogen ion concentration of 10 mol/dm: such a ""solution"" would have a density more than a hundred times greater than a neutron star. Rather, ""H"" = −21 implies that the reactivity (protonating power) of the solvated hydrogen ions is 10 times greater than the reactivity of the hydrated hydrogen ions in an"
"Potassium hydrogen phthalate Potassium hydrogen phthalate, often called simply KHP, is an acidic salt compound. It forms white powder, colorless crystals, a colorless solution, and an ionic solid that is the monopotassium salt of phthalic acid. KHP is slightly acidic, and it is often used as a primary standard for acid-base titrations because it is solid and air-stable, making it easy to weigh accurately. It is not hygroscopic. It is also used as a primary standard for calibrating pH meters because, besides the properties just mentioned, its pH in solution is very stable. It also serves as a thermal standard"
"the Hammett acidity function, ""H"", 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 model uses the Lewis acid–base definition. This scale applies to liquids, gases and even solids. In 2010, a new ""unified absolute pH scale"" has been proposed that would allow various pH ranges across different solutions to use a common proton reference standard. 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,"
"a pH level of 4~5.5. The neutral level that is not harmful to the humans is pH 7, meaning that these papers are acidic. If papers have low pH level (more acidic), they are completely decomposed in 100 years. Hanji, however, uses Hibiscus Manihot, which has a pH level of 7 and does not get dismantled easily (“The Significance”). Ever since paper was first introduced to the commoners in ancient Koreans, its uses have been adapted into various and unique ways. Hanji was used to help people in the daily lives. They covered their door frame with Hanji and controlled"
"pH value below 7.0 are considered acidic and solutions with pH value above 7.0 are basic (alkaline). As most naturally occurring organic compounds are weak protolytes, carboxylic acids and amines, pH indicators find many applications in biology and analytical chemistry. Moreover, pH indicators form one of the three main types of indicator compounds used in chemical analysis. For the quantitative analysis of metal cations, the use of complexometric indicators is preferred, whereas the third compound class, the redox indicators, are used in titrations involving a redox reaction as the basis of the analysis. In and of themselves, pH indicators are"
"pH. Normal blood pH falls in the range of 7.35–7.45, so a number lower than this range represents acidosis and a higher number represents alkalosis. Enzymes, being the regulators or catalysts of virtually all biochemical reactions - are sensitive to pH and will change shape slightly with values outside their normal range. These variations in pH and accompanying slight physical changes to the active site on the enzyme decrease the rate of formation of the enzyme-substrate complex, subsequently decreasing the rate of many enzymatic reactions, which can have complex effects on HR. Severe changes in pH will lead to denaturation"
"two axes. The vertical axis is labeled E for the voltage potential with respect to the standard hydrogen electrode (SHE) as calculated by the Nernst equation. The ""H"" stands for hydrogen, although other standards may be used, and they are for room temperature only. The horizontal axis is labeled pH for the -log function of the H ion activity. The lines in the Pourbaix diagram show the equilibrium conditions, that is, where the activities are equal, for the species on each side of that line. On either side of the line, one form of the species will instead be said"
"get 5 points. Later, an average is taken from all the parameters of the country, giving the index a relative position of all the countries. Afterwards, all the values are classified using quartiles. A summary with the values of each country is presented below. The pH is a chemical parameter that measures the acidity or basicity of the water and is commonly measured in situ. Distilled water has a pH of 7, where less than 7 is considered acid and greater than 7 is considered basic. In most cases, low pH is due to organic overloading and low oxygen conditions"
"frequently weak acids or weak bases. The general reaction scheme of a pH indicator can be formulated as: Here, HInd stands for the acid form and Ind for the conjugate base of the indicator. The ratio of these determines the color of the solution and connects the color to the pH value. pH indicators that are weak protolytes, the Henderson–Hasselbalch equation for them can be written as: The equation, derived from the acidity constant, states that when pH equals the p""K"" value of the indicator, both species are present in a 1:1 ratio. If pH is above the p""K"" value,"
"and 0.65-0.85 for whites. The pH level of a wine is the measurement of the amount of free (H+) hydrogen ions. It is related to the titratable acidity level of a wine but differs in significant ways. Low pH numbers indicate a high concentration of acids in a solution. While pure water is neutral with a pH of 7, wine tends to be more acidic with a pH between 3 and 4. As the acid levels in ripening grapes fall, the concentration of acids are lessening which means the pH level is rising. Yeasts, bacteria, phenolic compounds such as anthocyanins"
"pH values. These commercial indicators (e.g., universal indicator and Hydrion papers) are used when only rough knowledge of pH is necessary. Tabulated below are several common laboratory pH indicators. Indicators usually exhibit intermediate colors at pH values inside the listed transition range. For example, phenol red exhibits an orange color between pH 6.8 and pH 8.4. The transition range may shift slightly depending on the concentration of the indicator in the solution and on the temperature at which it is used. The figure on the right shows indicators with their operation range and color changes. An indicator may be used"
"is not very dilute, so that the concentration of [OH] ions can be neglected. This is equivalent to the assumption that the final pH will be below about 6 or so. See Calculations of pH for more details. First write down the equilibrium expression. This is generally regarded as the 'R'. The columns of the table correspond to the three species in equilibrium. The first row, labeled I, has the initial conditions: the ""nominal concentration"" of acid is C and it is initially undissociated, so the concentrations of A and H are zero. The second row, labeled C, specifies the"
"as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator. There are three current theories used to describe acid–base reactions: Arrhenius, Bronsted-Lowry and Lewis when determining pH. The concept of pH was first introduced by the Danish chemist Søren Peder Lauritz Sørensen at the Carlsberg Laboratory in 1909 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: p. The"
"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. 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"
"10 moles of OH per litre; since the two concentrations are equal, they are said to neutralise each other. A pH of 9.5 has 10 moles hydrogen ions per litre of solution (and also 10 mole per litre OH). A pH of 3.5 has one million times more hydrogen ions per litre than a solution with pH of 9.5 (9.5 - 3.5 = 6 or 10) and is more acidic. The effect of pH on a soil is to remove from the soil or to make available certain ions. Soils with high acidity tend to have toxic amounts of aluminium"
"has an alkaline pH of 11 to 12. The high pH is interpreted to be a consequence of serpentinization of chondritic rock that leads to the generation of H, a geochemical source of energy that can support both abiotic and biological synthesis of organic molecules such as those that have been detected in Enceladus's plumes. Following ""Voyager's"" encounters with Enceladus in the early 1980s, scientists postulated that it may be geologically active based on its young, reflective surface and location near the core of the E ring. Based on the connection between Enceladus and the E ring, scientists suspected that"
"exact meaning of the ""p"" in ""pH"" is disputed, but according to the Carlsberg Foundation, pH stands for ""power of hydrogen"". 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"
"of the acidity or alkalinity of the soil. More precisely, it is a measure of hydrogen ion concentration in an aqueous solution and ranges in values from 0 to 14 (acidic to basic) but practically speaking for soils, pH ranges from 3.5 to 9.5, as pH values beyond those extremes are toxic to life forms. At 25 °C an aqueous solution that has a pH of 3.5 has 10 moles H (hydrogen ions) per litre of solution (and also 10 mole/litre OH). A pH of 7, defined as neutral, has 10 moles hydrogen ions per litre of solution and also"
"HSO (18.4 M) has a ""H"" value of −12, and pyrosulfuric acid has ""H"" ~ −15. Take note that the Hammett acidity function clearly avoids water in its equation. It is a generalization of the pH scale—in a dilute aqueous solution (where B is HO), pH is very nearly equal to ""H"". By using a solvent-independent quantitative measure of acidity, the implications of the leveling effect are eliminated, and it becomes possible to directly compare the acidities of different substances (e.g. using p""K"", HF is weaker than HCl or HSO in water but stronger than HCl in glacial acetic acid.)"
"the solution determines pH. Weak bases will have a higher H concentration because they are less completely protonated than stronger bases and, therefore, more hydrogen ions remain in the solution. If you plug in a higher H concentration into the formula, a low pH results. However, pH of bases is usually calculated using the OH concentration to find the pOH first. This is done because the H concentration is not a part of the reaction, while the OH concentration is. By multiplying a conjugate acid (such as NH) and a conjugate base (such as NH) the following is given: Since"
"more completely and are thus stronger bases. As stated above, pH of the solution depends on the H concentration, which is related to the OH concentration by the self-ionization constant (K = 1.0x10). A strong base has a lower H concentration because they are fully protonated and less hydrogen ions remain in the solution. A lower H concentration also means a higher OH concentration and therefore, a larger K. NaOH (s) (sodium hydroxide) is a stronger base than (CHCH)NH (l) (diethylamine) which is a stronger base than NH (g) (ammonia). As the bases get weaker, the smaller the K values"
"Soil pH Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions ( or, more precisely, ) in a solution. In soils, it is measured in a slurry of soil mixed with water (or a salt solution, such as 0.01 M ), and normally falls between 3 and 10, with 7 being neutral. Acid soils have a pH below 7 and alkaline soils have a pH above 7. Ultra-acidic soils (pH < 3.5) and very strongly alkaline soils (pH > 9)"
"to a pH-electrode: The pH range at constant concentration can be divided into 3 parts: where F is Faraday's constant (see Nernst equation). The effect is usually noticeable at pH > 12, and concentrations of lithium or sodium ions of 0.1 moles per litre or more. Potassium ions usually cause less error than sodium ions. Specialized electrodes exist for working in extreme pH ranges. A typical modern pH probe is a combination electrode, which combines both the glass and reference electrodes into one body. The combination electrode consists of the following parts (see the drawing): The bottom of a pH"
"Intracellular pH Intracellular pH (pHi) is the measure of the acidity or basicity (i.e., pH) of intracellular fluid. The pHi plays a critical role in membrane transport and other intracellular processes. The mechanisms that regulate pHi are usually considered to be plasma membrane transporters of which two main types exist — those that are dependent and those that are independent of HCO. Physiologically normal intracellular pH is most commonly between 7.0 and 7.4, though there is variability between tissues (e.g., mammalian skeletal muscle tends to have a pHi of 6.8-7.1). Intracellular pH is typically lower than extracellular pH due to"
"instructions for cleaning and maintaining their probe designs. For illustration, one maker of laboratory-grade pH gives cleaning instructions for specific contaminants: general cleaning (15-minute soak in a solution of bleach and detergent), salt (hydrochloric acid solution followed by sodium hydroxide and water), grease (detergent or methanol), clogged reference junction (KCl solution), protein deposits (pepsin and HCl, 1% solution), and air bubbles. The German Institute for Standardization publishes a standard for pH measurement using pH meters, DIN 19263. Very precise measurements necessitate that the pH meter is calibrated before each measurement. More typically calibration is performed once per day of operation."
"pharmaceutical, beverage, plastic and petroleum industries. APHA color APHA color, also referred to as the Hazen scale, and more appropriately as the Platinum Cobalt(Pt/Co) scale, is a color standard named for the American Public Health Association and defined by ASTM D1209. It was originally intended to describe the color of waste water, but its usage has expanded to include other industrial applications. APHA color is a color scale sometimes referred to as a ""yellowness index"" that is used to assess the quality of liquids that are clear to yellowish in color. It is similar to the Hazen color test, to"
"PH meter A pH meter is a scientific instrument that measures the hydrogen-ion activity in water-based solutions, indicating its acidity or alkalinity expressed as pH. The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, and so the pH meter is sometimes referred to as a ""potentiometric pH meter"". The difference in electrical potential relates to the acidity or pH of the solution. The pH meter is used in many applications ranging from laboratory experimentation to quality control. The rate and outcome of chemical reactions taking place in water often depends on the"
"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. The pH of seawater is typically limited to a range between 7.5 and 8.4. It plays an important role in the ocean's carbon"
"pH, a scale for measuring acidity and basicity of substances. While working at the Carlsberg Laboratory, he studied the effect of ion concentration on proteins, and understood the concentration of hydrogen ions was particularly important. To express the hydronium ion (H3O+) concentration in a solution, he devised a logarithmic scale known as the pH scale. Carlsberg Laboratory The Carlsberg Laboratory in Copenhagen, Denmark, was created in 1875 by J. C. Jacobsen, the founder of the Carlsberg brewery, for the sake of advancing biochemical knowledge, especially relating to brewing. It featured a Department of Chemistry and a Department of Physiology. In"
"diets mainly composed of vegetables tend to produce alkali urine. Commercial brands measure pH in increments of 0.5 or 1 pH units between pH 5 and 9. In order to differentiate pH in this wide range it is common to use a double indicator system comprising methyl red and bromothymol blue. Methyl red produces a colour change from red to yellow in the range of pH 4 to 6 and the bromothymol blue changes from yellow to blue between pH 6 and 9. In the range 5 to 9 the strips show colours that change from orange at pH 5,"
"Fecal pH test A fecal pH test is one where a specimen of feces is tested for acidity in order to diagnose a medical condition. Human feces is normally acidic. An acidic stool can indicate a digestive problem such as lactose intolerance or a contagion such as ""E. coli"" or rotavirus, or overgrowth of the acid producing bacteria (such as lactic acid bacteria for instance). The average pH for a healthy person is a pH of 6.6. The test is fast and can be performed in a doctor's office. A patient must not be receiving antibiotics. At least half a"