A supply of NaOH contains the contaminants NaCl and MgCl2. A 4.9995g sample of this material is dissolved and diluted to 500mL, 20mL of this is titrated with 22.26mL of a 0.1989M solution of HCl. What is the percent NaOH of the original solution?

1 Answer
May 6, 2015

88.5%

22.26 ml of 0.1989M HCl contain 0.022260.1989=4.427103 moles of HCl. Each mole of HCl titrate 1 mole of NaOH. If 20 ml of the solution contains 4.427103 moles, in 500 ml there were 0.1107 moles of NaOH. The weight of NaOH in the sample is 0.110740(MMofNaOH)=4.4275 g
4.9995 g of crude material contain 4.4275 g of NaOH, therefore 4.42754.9995100=88.55%