Question

The titration of 45.00 mL a 0.250 M KOH solution required 21.32 mL of H2SO4 to reach the endpoint. What is the concentration of the H2SO4?
Thank you

Answer 1

Molarity = moles of solute/volume of solution in liter ..............(1)

Moles of KOH = Molarity of KOH x Volume of KOH in Litre

= 0.25 x 0.045

= 0.01125 mole

For the end point,

moles of KOH = moles of H2SO4 / 2 ............. (2 moles of KOH is required to neutralize 1 mole of H2SO4)

Moles of H2SO4 = 0.01125/2 moles

= 0.005625 moles

Concentration of H2SO4 = 0.005625/0.02132 .........from (1)

= 0.263836 M

Shorcut: N1V1 = N2V2

Molarity = Normality / valency

N2 = 45 X 0.25/ 21.32

= 0.52767 N

molarity of H2SO4 = 0.52767/2 = 0.263836 M