Number of moles of NaOH , n = Molarity x volume in L
                                          Â
= 0.100 M x (40.50 /1000) L
                                          Â
= 4.05x10-3 mol
H2Z(aq) + 2 NaOH(aq) → Na 2Z(aq) + 2 H2O(ℓ)
From the balanced equation ,
2 moles of NaOH reacts with 1 mole of H2Z
4.05x10-3 mol of NaOH reacts with
(4.05x10-3 )/2 = 2.025 x10-3 mole of
H2Z
Given mass of H2Z is 0.250 g
We know that Number of moles , n = mass / molar mass
             Â
Molar mass = mass / number of moles
                            Â
    = 0.250 g / (2.025 x10-3
mol)
                                                 Â
= 123.46 g/mol
Therefore the molarmass of H2Z is 123.46 g/mol
