PH indicator

A pH indicator is a special kind of chemical that can change color when it comes into contact with something that is either acid or alkaline. For example, if you mix red cabbage juice with acid, the juice will turn a different color. The same thing happens when you mix red cabbage juice with something that is alkaline. You can use an indicator to tell you when something is acidic or alkaline, which is helpful for scientists when they are working in a lab.