Test different substances and see their pH, colour with indicators, and position on the scale
7.0
Neutral
Pure water
0 Strong acid7 Neutral14 Strong base
The pH scale: pH measures how acidic or basic a substance is. Values below 7 are acidic (more H⁺ ions), 7 is neutral, and above 7 is basic/alkaline (more OH⁻ ions). Each whole number change represents a tenfold change in acidity — pH 3 is 10 times more acidic than pH 4.