Exactly what that reaction is depends upon the indicator, and the pH range.

First, what is an acceptable pH range for hand/body soap?

The pH range for the typical calcium reactor is 6.5 - 6.8.

It grows in many different soil types, and can handle a wide pH range.

Most plants thrive in a slightly acid pH range of 6 to 7.

Alumina is unstable in the pH range from 7 to 11.

Rutile is unstable in the pH range from 2 to 6.

The lower limit of the pH range is about 4.0.

The procedure is then repeated with this phase at the opposite pH range.

Many life forms have a relatively small pH range; an example of a buffer solution is blood.