Question

Calculate the percentage composition of hydrogen, sulphur and oxygen in Sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$.

Given : Atomic weight of H = 1u, S = 32u, O = 16u

Answer 1

Step 1: Given data

Atomic weight of H = 1u, S = 32u, O = 16u

Step 2: Finding the mass for the given data

The molecular mass of $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ = (Number of hydrogen atoms x atomic mass of hydrogen) + (Number of sulphur atoms x atomic mass of sulphur) + (Number of oxygen atoms x atomic mass of oxygen)

The molecular mass of $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ = $\left(2\times 1\right)+\left(1\times 32\right)+\left(4\times 16\right)$

The molecular mass of $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ = $2+32+64=98$u

Step 3: Finding the mass for each element

Mass of $\mathrm{H}$ = (Number of hydrogen atoms x atomic mass of hydrogen) $=\left(2\times 1\right)=2u$

Mass of $\mathrm{S}$ = (Number of sulphur atoms x atomic mass of sulphur) $=\left(1\times 32\right)=32u$

Mass of $\mathrm{O}$ = (Number of oxygen atoms x atomic mass of oxygen) $=\left(4\times 16\right)=64u$

Step 4: Finding the % composition

% composition is the proportion by mass of each element present in a compound.

% composition of $\mathrm{H}=\frac{2}{98}=2.04\%$

% composition of $\mathrm{S}=\frac{32}{98}=32.65\%$

% composition of $\mathrm{O}=\frac{64}{98}=65.3\%$

Thus, the percentage composition of oxygen, hydrogen, sulphur and oxygen in Sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ is $2.04\%,32.65\%\mathrm{and}65.3\%$respectively.