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 −log10 c, where c is the hydrogen ion concentration in moles per litre.
- 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.