Question

What is the percent composition of Oxygen in Ammonium Oxide?

Answer 1

Step 1 - Discovering the ionic formula of Ammonium Oxide

Ammonium Oxide is formed by the ionic bonding between Ammonium (NH4(+)) and Oxide (O(2-)):

$2NH^+_4+O^{2-}\rightarrow(NH_4)_2O^{}_{}$

Step 2 - Finding its molar mass

To find the molar mass of a substance, we need to multiply the molar mass of each element by the number of times it appears in the formula and, finally, sum it all up. The molar masses are 14 g/mol for N; 1 g/mol for H and 16 g/mol for O. We have thus:

$\begin{gathered} N\rightarrow2\times14=28 \\ \\ H\rightarrow8\times1=8 \\ \\ O\rightarrow1\times16=16 \end{gathered}$

The molar mass of (NH4)2O will be thus:

$M=28+8+16=52\text{ g/mol}$

Step 3 - Finding the percent composition of Oxygen

As we saw in step 2, the molar mass of ammonium oxide is 52 g/mol. From this mass, 16 g/mol come from Oxygen. We can calculate the percent composition of Oxygen by setting the following proportion:

$\begin{gathered} 52\text{ g/mol ---- 100\%} \\ 16\text{ g/mol ---- x} \\ \\ x=\frac{100\times16}{52}=\frac{1600}{52}=30.8\text{ \%} \end{gathered}$

The percent composition of Oxygen is thus 30.8 %.