Question

if a 4.000gram sample potassium acid phthalate is equivalent to 48.37 ml of a sodium hydroxide solution, what is the concentration of the latter?

Answer 1

The molecular formula of is ‎potassium acid phthalate C₈H₅KO₄

Molar mass of potassium acid phthalate is 204 g/mol

So number of moles of potassium acid phthalate , n = mass/molar mass

                                                                            = 4.000 g / 204 (g/mol)

                                                                           = 0.0196 mol

Which is equivalent to 48.37 ml of NaOH

So Molarity of NaOH ,M = number of moles / volume in L

                                    = 0.0196 mol / ( 48.37/1000) L

                                    = 0.405 M

Therefore the molarity of NaOH is 0.405 M