Question

A student placed 10 g of Mg(OH)2 into a flask and added 500ml of water. The student took 100 ml of the Mg(OH)2 solution and reacted with HCl(aq). If 13.75 ml of 0.010M HCL reacted with the OH(aq), was was the concentration of hydroxide ion in the 100 ml solution?

Answer 1

2HCl + Mg(OH)2 ==> MgCl2 + 2H2O
moles HCl = M x L
moles Mg(OH)2 = moles HCl x (1/2)
moles OH^- = 2 x moles Mg(OH)2.