# Help Zone

### Student Question

Hi! I'm not sure I understand how pH works.

Is the higher, the more acidic?

And if for example I have a solution with a pH of 4 and another with a pH of 8, is the second solution twice as acidic as the first?

Chemistry ## Explanations (1)

• Explanation from Alloprof  Explanation from Alloprof

This Explanation was submitted by a member of the Alloprof team.

Hello!

First, pH is the potential of hydrogen in a solution. Its scale measures the H + ion concentration. It ranges from 0 to 14, where zero is the highest level of acidity and 14 the lowest.

To answer your question, the higher the concentration of H + ions in a solution, the more acidic it is and the lower is its pH.

The pH scale is logarithmic. This means that each pH rung is 10 times more basic than its previous one if we go up in ascending order, and 10 times more acidic if we go down the scale in descending order.

A substance of pH 4 has an H + ion concentration of 0.0001 mol / L, while a substance of pH 8 has an H + ion concentration of 0.000000 01 mol / L. The second solution is therefore 1000 times more basic than the first.