pH of Strong Acids

Key Concepts

What is pH?

pH is a measure of the concentration of hydrogen ions in a solution. It reflects how acidic or alkaline a solution is using a logarithmic scale.

The pH Scale

• The pH scale typically ranges from 0 to 14.

• Lower pH means higher   (more acidic).

• Higher pH means lower   (more alkaline).

Because the pH scale is logarithmic, a change of  pH unit means the hydrogen ion concentration changes by a factor of .

To calculate pH from hydrogen ion concentration:

Where:

is the concentration of hydrogen ions in .

To calculate   from pH, use the inverse log:

Strong Acids and [H⁺]

Strong acids are fully dissociated in water.

• For a monoprotic strong acid,

  • = acid concentration

    because 1 mole of acid gives 1 mole of  .

• For a diprotic strong acid,

  • acid concentration

  • because each molecule releases 2 moles of 

Worked Examples

Quick Recap Table