Two solutions are combined, 100 ml of 1 M NaOH and 100 ml of 1.5 M H2SO4. What is leftover, H+ or OH-, and what is its concentration in the solution?

Question

The balanced equation is 2NaOH + H2SO4 -> Na2SO4 + 2 H20

Answer 1

2NaOH + H₂SO₄ ==> Na₂SO₄ + 2H₂0

moles NaOH used = 0.1 L x 1 mole/L = 0.1 moles NaOH

moles H2SO4 used = 0.1 L x 1.5 mol/L = 0.15 moles H2SO4

Since they react is a 2 mole NaOH to 1 mole H2SO4 ratio, the NaOH is in limiting supply, so there will be excess H2SO4.

moles H2SO4 that have reacted = 0.1 moles NaOH x 1 moles H2SO4/2 moles NaOH = 0.05 moles H2SO4 reacted.

moles H2SO4 left over = 0.15 moles - 0.05 moles = 0.1 moles H2SO4 left over.

The concentration of H+ left over = 0.1 moles H2SO4 x 2 moles H/mole H2SO4/0.2 L = 1 M H+

This last calculation is based on 2 moles of H+ from each mole of H2SO4 and the fact that the final volume is 200 ml or 0.2L.