ANDREW LAMBERT PHOTOGRAPHY / SCIENCE PHOTO LIBRARY ANDREW LAMBERT PHOTOGRAPHY / SCIENCE PHOTO LIBRARY
Pupil measuring pH. Schoolboy using a digital pH meter to measure the pH of dilute ethanoic (acetic) acid. The display shows 2.9, indicating that this is a moderately strong acid. It runs from 1 (most acidic) to 14 (most alkaline). Water is considered neutral (pH 7). Ethanoic acid is found in vinegar.
Model release available. Property release not required.