In Step 5, you will calculate H+/OH - ratios for more extreme pH solutions. Find the concentration of H + ions to OH - ions listed in Table B of your Student Guide for a solution at a pH = 2. Then divide the H + concentration by the OH - concentration. Record these concentrations and ratio in Table C. What is the concentration of H + ions at a pH = 2? mol/L What is the concentration of OH - ions at a pH = 2? mol/L What is the ratio of H + ions to What is the concentration of H + ions at a pH = 11?

You must know the concept of pH of a solution and its relation to the concentration of H + and OH - ions. pH is a measure of the substance's acidity or basicity. From the definition of Arrhenius, an acid contains an H + while a base contains a OH - ion. From this definition, we can say that an acidic substance has a higher concentration of H + ions. Now, I'll introduce here that pH is the value of the negative logarithm of the concentration of H+. In equation,

pH = - log[H+]

The term pOH is therefore also, pOH = - log[OH-]. Therefore, the relationship that connects the two negative logarithms is:

pH + pOH = 14

The pH scale starts from 1 being the most acidic to 14 being the most basic. The neutral pH is 7. Thus, for a pH of 7, the H + and the OH - concentrations are equal.

pH = 7 = - log[H+][H+] = 1*10⁻⁷ mol/L = [OH-]

Since the concentrations are equal, the ratio is equal to 1.