A student prepared a stock solution by dissolving 10.0 g of KOH in enough water to make 150. mL of solution. She then took 15.0 mL of the stock solution and diluted it with enough water to make 65.0 mL of a final solution. What is the concentration of KOH for the final solution?

Question

Quizplus · Accepted Answer

First, calculate the molarity of the stock solution: Molar mass of KOH = 56.11 g/mol. Moles of KOH = 10.0 g / 56.11 g/mol = 0.178 mol. Molarity of stock solution = 0.178 mol / 0.150 L = 1.187 mol/L. Then, use the dilution formula M1V1 = M2V2: (1.187 mol/L)(0.015 L) = M2(0.065 L). Solving for M2 gives M2 = 0.274 mol/L.

A Student Prepared a Stock Solution by Dissolving 10