How many moles of pure NaOH must be used to prepare 1.0 L of a solution that has pH = 12.00?

Answer 1

To find the number of moles of NaOH needed, we first need to determine the concentration of OH- ions in the solution.

Since pH is defined as the negative logarithm of the hydrogen ion concentration (pH = -log[H+]), we can determine the hydroxide ion concentration by taking the negative antilog of the pH value:

OH- concentration = 10^-pOH

Since pH + pOH = 14, the pOH can be calculated as:

pOH = 14 - pH = 14 - 12.00 = 2.00

Therefore, the hydroxide ion concentration is:

OH- concentration = 10^-pOH = 10^-2.00

Now, we can calculate the moles of NaOH needed to achieve this concentration in a 1.0 L solution.

Moles = (OH- concentration) x (volume in liters)

Moles = (10^-2.00) x (1.0 L)

Moles = 0.01 moles

Therefore, 0.01 moles of pure NaOH must be used to prepare 1.0 L of a solution with a pH of 12.00.