Question

0.80 grams of KHP is titrated with 20 mL of the unknown NaOH solution. What is the molarity of the NaOH solution in mol/mL?

Answer 1

KHP is an abbreviation for KHC₈H₄O₄, potassium hydrogen phthalate

The mass of KHP given is , m = 0.80 g

Molar mass of KHP,r KHC₈H₄O₄ is 39+1+(8x12) + (4x1)+(4x16) = 204 g/mol

So number of moles of KHP , n = mass/molar mass

                                             = 0.80 g / 204(g/mol)

                                             = 3.92x10^-3 mol

The balanced equation is    KHC₈H₄O₄ + NaOH KNaC₈H₄O₄ + H₂O

According to the balanced equation ,

1 mole of KHP reacts with 1 mole of NaOH

3.92x10^-3 mol of KHP reacts with 3.92x10^-3 mole of NaOH

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

                               = (3.92x10^-3 mol ) / (20/1000)L

                               = 0.196 M

Therefore the molarity of NaOH solution is 0.196 M