Question

Calculate the normality of 4.0 molar sulphuric acid solution.​

Answer 1

Answer:

Normality is a variation of molarity that includes an equivalence factor.

It is supposed to be calculated by Normality=M/f, where f is an equivalence factor.

Take sulfuric acid, for example. Since 0.5 mol of sulfuric acid is used to neutralize OH-, the factor is 0.5.

I do not like this format so I like to define it this way: Each sulfuric acid releases two protons so 1 mol of H2SO4 gives 2 mol of H+. The concentration of H+ is the normality.

Using this format we can see that 1 M HCl is 1 N HCl, 1 M NaOH is 1 N NaOH, 1 M H3PO4 is 3 N, 1 M of Ca(OH)2 is 2 N.

I think you see the trend. The number of protons or hydroxide released gives normality. So in reference to your question, since sulfuric acid releases 2 protons per molecule, the molarity is half the normality. 0.4 N H2SO4 is 0.2 M H2SO4.

Chemists don’t tend to use normality much. I first experienced it in my soil science lab and then again in a biology lab. It seems to me, chemists know how to multiply or divide by the number of protons or hydroxides released. We can do stoichiometry. But non-chemists tend to like to just compare the numbers. “Oh I need to neutralize 50 mL of one molar NaOH. Well if I use this 1 N sulfuric acid, I only need 50 mL of it. Or I can use 25 mL of 2 N sulfuric acid.”