Question

In a titration of 20.00 mL of 0.1451 M H2SO4, 45.77 mL of an NaOH solution are needed. What is the concentration of the NaOH solution?

Answer 1

Number of moles of H₂SO₄ is , n = molarity x volume in L

                                       = 0.1451 M x 0.020 L

                                    = 0.0029 moles

H₂SO₄ + 2NaOH Na₂SO₄ + 2H₂O

According to the balanced equation ,

1 mole of H₂SO₄ reacts with 2 moles of NaOH

0.0029 mole of H₂SO₄ reacts with M moles of NaOH

M = ( 2x0.0029) / 1

    = 0.0058 moles

Given Volume of NaOH , V = 45.77 mL = 45.77/1000 mL = 0.04577 mL

So Molarity of NaOH is , M = number of moles / volume of the solution

                                        = 0.0058 mol / 0.04577 L

                                        = 0.127 M

Therefore the molarity of NaOH solution is 0.127 M