If you made up a solution of NaOH by adding 0.010 mole of solid NaOH to 1.0 liter of distilled water, what would be the concentration of the OH - (aq) ?

Answer is 0.01 M.

Explantion:

NaOH is a strong base which fully dissociates into its ions in water as Na⁺ and OH⁻.

NaOH (s) → Na⁺ (aq) + OH⁻ (aq)

The stoichiometric ratio between NaOH (s) and OH⁻ (aq) is 1 : 1.

Hence,

moles of OH⁻ (aq) = moles of NaOH (s)

= 0.010 mol

Concentration (M) = moles of solute (mol) / volume of the solution (L)

Hence,

concentration of OH⁻ (aq) = 0.010 mol / 1.0 L

= 0.01 M