Question

If a 23.7 mL solution of H2SO4 has a concentration of 0.100 M, what is its pH? Also, how

many grams of H2SO4 are in the solution?

Answer 1

Concentration is how many moles there are per unit volume, therefore, find the quantity of substance:

$$n=CV.$$

The mass is the product of molar mass and n:

$$m=n\Mu=CV\Mu=\\=0.1(23.7\cdot10^{-3})(1\cdot2+32+16\cdot4)=0.232\text{ g}.$$

The pH is the negative decimal logarithm of hydrogen ion concentration in the solution. The sulphuric acid dissociates into two ions, both of the same and equal concentration of 0.100 M:

$$\text{H}_2\text{SO}_4=\text{H}^++\text{HSO}_4^-, \\ \text{pH}=-\text{lg}[\text{H}^+]=-\text{lg}[0.100]=1.$$