Question

A student found that it required 36.0 mL of a NaOH solution to neutralize 25.0 mL of a 0.850 M H2SO4 solution which react according to the equation: 2 NaOH + H2SO4 = Na2SO4+ 2H2O. The molarity of the sodium hydroxide solution is:

Answer 1

To answer this question we can use the titration formula, which is:

Ma * Va = Mb * Vb

Where:

Ma = molarity of acids

Va = volume of acids

Mb = molarity of bases

Vb = volume of bases

We have the molarity and volume of the acid, and the volume of the base, now let's add to our equation:

0.850M * 25.0 mL = 36.0 mL * Mb

But there is a small detail here, if you check the reaction you will see that the ratio is 2:1, so for every molecule of H2SO4 in a reaction, I will need 2 molecules of NaOH in the reaction so that it all can go forward, and for every NaOH, you will need 1/2 of H2SO4 to move forward in the reaction. So we will add this "2" in the equation.

(0.850M * 25.0 mL)/2 = 36.0 mL * Mb

21.25/2 = 36Mb

10.625 = 36Mb

Mb = 0.295M

Therefore, according to the titration formula, we will have 0.295 of molarity of NaOH in the reaction.