What is the concentration of excess H2SO4when50cm3 of 0.200moldm-3 NaOH is added to 40cm3 of 0.250 moldm-3 H2SO4.?

Answer 1

moles H2SO4 = 0.040 L x 0.250 mol/L = 0.01 moles H2SO4moles NaOH = 0.05 L x 0.200 mol/L = 0.01 moles NaOH

Reaction: 2NaOH + H2SO4 = Na2SO4 + 2H2O

It takes 2 moles NaOH for each 1 mole H2SO4

Moles H2SO4 used up by 0.01 moles NaOH = 0.005 moles

moles H2SO4 remaining = 0.005 moles H2SO4

Total volume = 50 cm3 + 40 cm3 = 90 cm3 = 0.090 L

Final [H2SO4] = 0.005 moles/0.090 L = 0.055 M (to 2 significant figures)