A 50.00-mL volume of 0.4987 M HCl was added to a 5.436-g sample of milk of magnesia.

Question:

A 50.00-mL volume of 0.4987 M HCl was added to a 5.436-g sample of milk of magnesia. This solution was then titrated with 0.2456 M NaOH. If it required 39.42 mL of NaOH to reach the endpoint, what was the mass percentage of Mg(OH)2 in the milk of magnesia?