A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid, and higher values more alkaline. The pH is equal to log₁₀c, where c is the hydrogen ion concentration in moles per liter.
- ‘Prof. Lilley who had no experience in measuring the pHs of surfactant solutions having a high solids content was surprised to see a 0.3 difference in measurements.’
- ‘At relatively alkaline pHs (found under stress), even very low ABA concentrations found in the xylem of well-watered plants will limit leaf growth rate.’
- ‘Additionally, another 5 to 16% is excreted daily into the gastric juices, since TCAs have a pK a of 9.5 and are highly ionized at acid pHs, thereby favoring concentration in the acid stomach.’
- ‘At specific concentrations and pHs, these dyes identified the distribution of macromolecules such as proteins, lipids, nucleic acids, or polysaccharides in the developing egg chamber and other tissues.’
- ‘Non-enzymatic reduction of DHA by reduced glutathione in phosphate buffers of different pHs was also measured in a separate cuvette at the same time.’
Early 20th century: from p representing German Potenz power + H, the symbol for hydrogen.
We take a look at several popular, though confusing, punctuation marks.