Chapter SH, Problem 18.12APP

To determine

To calculate: the percentage of mass of sulfur in a sulfuric acid molecule.

Answer to Problem 18.12APP

  $32.65\%$ of the mass of a sulfuric acid molecule is sulfur.

Explanation of Solution

Given data:

Atomic mass of hydrogen, ${\text{M}}_H=\text{1 a}\text{.m}\text{.u}$

Atomic mass of oxygen, ${\text{M}}_O=\text{16 a}\text{.m}\text{.u}$

Atomic mass of sulfur, ${\text{M}}_S=\text{32 a}\text{.m}\text{.u}$

Formula used:

Molecular mass of a compound is the sum of the atomic masses of all the atoms in the compound.

Calculation:

As per the problem,

In a molecule of sulfuric acid, there are two atoms of hydrogen, one atom of sulfur and four atoms of oxygen.

Add the mass of each atom to find the molecular mass of sulfuric acid.

Molecular mass of ${\text{H}}_2{\text{SO}}_4$

  $\begin{array}{l}=(2\times {\text{M}}_H)+(1\times {\text{M}}_S)+(4\times {\text{M}}_O)\\ =(2\times 1\text{ a}\text{.m}\text{.u)+(1}\times 32\text{ a}\text{.m}\text{.u)+(4}\times \text{16 a}\text{.m}\text{.u)}\\ =\text{98 a}\text{.m}\text{.u}\end{array}$

Percentage of sulfur in one molecule of sulfuric acid

  $\begin{array}{l}=\frac{\text{ mass of sulfur}}{\text{mass of sulfuric acid}}\times 100\\ =\frac{32\text{ a}\text{.m}\text{.u}}{\text{98 a}\text{.m}\text{.u}}\times 100\\ =32.65\%\end{array}$

Conclusion:

  $32.65\%$ of the mass of a sulfuric acid molecule is sulfur.