1. Calculate the moles of NaOH:
* Molar mass of NaOH: 22.99 g/mol (Na) + 16.00 g/mol (O) + 1.01 g/mol (H) = 40.00 g/mol
* Moles of NaOH: (0.240 g NaOH) / (40.00 g/mol) = 0.00600 mol NaOH
2. Calculate the molarity of NaOH:
* Molarity: (0.00600 mol NaOH) / (0.225 L solution) = 0.0267 M NaOH
3. Relate NaOH concentration to OH- concentration:
* NaOH dissociates completely in water, producing one OH- ion for every NaOH molecule:
NaOH(aq) → Na+(aq) + OH-(aq)
* Therefore, the concentration of OH- ions is equal to the concentration of NaOH:
[OH-] = 0.0267 M
Therefore, the concentration of OH- in the solution is 0.0267 M.
