Question

A 29.0-g sample of NaOH is dissolved in water, and the solution is diluted to give a final volume of 1.60 L. The molarity of the final solution isA) 18.1 M B) 0.453 M C) 0.725 M D) 0.0552 M E) 0.862 M

Answer 1

Given mass of NaOH , m = 29.0 g

MOlar mass of NaOH is = At.mass of Na + At.mass of O + At.mass of H

                                       = 23 + 16 + 1

                                      = 40 g/mol

So the number of moles of NaOH , n = mass/molarmass

                                                           = 29.0 g / 40 (g/mol)

                                                           = 0.725 mol

Volume of the solution , V = 1.60 L

Molarity of the solution , M = number of moles / volume in L

                                          = 0.725 mol / 1.60 L

                                          = 0.453 mol / L

                                         = 0.453 M

So Molaity of the solution is 0.453 M

Therefore option (B) is correct.