The pH scale is a crucial tool in chemistry, measuring the acidity or alkalinity of solutions through hydrogen ion concentration. Introduced by Søren Sørensen, it ranges from 0 to 14, with 7 being neutral. The Brønsted-Lowry theory defines acids and bases by their proton exchange, impacting pH levels. Understanding pH is vital for applications in food science, pharmaceuticals, and environmental science, with pH meters and indicators aiding measurement.
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The pH scale is a measurement of the acidity or alkalinity of a solution based on the concentration of hydrogen ions
The term 'pH' is derived from the phrase 'potentia hydrogenii', meaning 'power of hydrogen'
The pH scale ranges from 0 to 14, with values below 0 or above 14 being possible but less common
Acids are substances that donate protons, while bases accept them, according to the Brønsted-Lowry theory
The potency of an acid or base is determined by its ability to dissociate in an aqueous solution
Strong acids, such as hydrochloric acid, nitric acid, and sulfuric acid, fully dissociate to release a significant concentration of hydrogen ions, while strong bases like sodium hydroxide dissociate to produce hydroxide ions
The pH of a strong acid can be calculated by determining the molar concentration of hydrogen ions in the solution
To find the hydrogen ion concentration from a known pH, the equation is rearranged to [H+] = 10^-pH
The pH of acid-base mixtures can be determined by identifying the limiting reactant and calculating the concentration of the remaining hydrogen or hydroxide ions after the reaction
Universal indicators, composed of a blend of dyes, provide an approximate pH value by exhibiting a color change at specific pH levels
pH meters measure the voltage difference between a reference electrode and a pH-sensitive electrode to determine the hydrogen ion concentration in a solution
Understanding pH and its measurement is crucial in fields such as food science, pharmaceuticals, and environmental science, enabling the analysis and control of chemical reactions and processes
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pH scale range
0 to 14; values can be <0 or >14 but are uncommon.
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Origin of 'pH' term
'potentia hydrogenii' meaning 'power of hydrogen'.
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pH value determination
Negative logarithm of hydrogen ion concentration: pH = -log10[H+(aq)].
