Question

What is the percent composition by mass of sulfur in ammonium sulfate (NH4)2SO4 ?
Responses

28%
28%

24%
24%

32%
32%

6.7%

Answer 1

To determine the percent composition by mass of sulfur in ammonium sulfate \((NH_4)_2SO_4\), we first need to calculate the molar mass of the compound.

The molar mass can be calculated as follows:

- Nitrogen (N): 14.01 g/mol
- Hydrogen (H): 1.008 g/mol
- Sulfur (S): 32.07 g/mol
- Oxygen (O): 16.00 g/mol

Now, let's break it down:

1. There are 2 nitrogen atoms: \(2 \times 14.01 = 28.02\) g/mol
2. There are 8 hydrogen atoms: \(8 \times 1.008 = 8.064\) g/mol
3. There is 1 sulfur atom: \(1 \times 32.07 = 32.07\) g/mol
4. There are 4 oxygen atoms: \(4 \times 16.00 = 64.00\) g/mol

Now, let's add these together to get the molar mass of ammonium sulfate:

\[
\text{Molar mass of } (NH_4)_2SO_4 = 28.02 + 8.064 + 32.07 + 64.00 = 132.154 \text{ g/mol}
\]

Now, we can calculate the percent composition by mass of sulfur:

\[
\text{Percent composition of S} = \left(\frac{\text{mass of S}}{\text{molar mass of compound}}\right) \times 100
\]

Substituting the values:

\[
\text{Percent composition of S} = \left(\frac{32.07}{132.154}\right) \times 100 \approx 24.25\%
\]

Thus, the answer is approximately \(24\%\).

The correct response is **24%**.