47.4 MB (3.7 MB compressed)
3342 x 4962 pixels
28.2 x 41.9 cm ⏐ 11.1 x 16.5 in (300dpi)
GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY
Universal indicator added to three test tubes containing different solutions (left to right): diluted hydrochloric acid (acidic), distilled water (weakly acidic) and diluted sodium hydroxide (alkaline). Universal indicator changes its colour depending on the pH of the solution. Red indicates a strong acid, yellow/orange indicates an acid, green is neutral, blue indicates an alkali, and purple indicates a strong alkali.
Model release not required. Property release not required.