Aquantity of 18.68 ml of koh solution is needed to neutralize 0.4218 g of khp. what is the concentration (in molarity) of the koh solution?

To neutralize an acidic substance with the basic solution, the number of moles should be equal. First, we calculate for the number of moles of KHP.

molar mass of KHP = (1 mol K)(39.1 g K/1 mol K) + (1 mol H)(1 g H/1 mol H) + (1 mol P)(30.97 g P / 1 mol P) = 71.07 g KHP/ mol

number of moles KHP = (0.4218 g KHP) x (1 mol KHP / 71.07 g KHP)
        n = 0.0059 moles

Let M be the molarity of the solution and equating the number of moles,
     0.0059 moles = (18.68 mL)(1 L/1000 mL)(M)
            M = 0.32 moles/L

ANSWER: 0.32 M