Question

Hydrogen sulfide gas (H2S) is a highly toxic gas that is responsible for the smell of rotten eggs. The volume of a container of hydrogen sulfide is 44.2mL. After the addition of more hydrogen sulfide, the volume increases to 98.5mL under constant pressure and temperature. The container now holds 1.97×10−3mol of the gas. How many grams of hydrogen sulfide were in the container initially? Give your answer in three significant figures.

Answer 1

Answer:  

$\boxed{\text{0.0301 g}}$

Step-by-step explanation:  

1. Calculate the initial moles of H₂S

We can use Avogadro's law: the number of moles of a gas is directly proportional to the volume if the pressure and temperature are constant.

$\dfrac{n_{1} }{V_{1}} = \dfrac{n_{2}}{V_{2}}\\\\\dfrac{n_{1}}{\text{44.2 mL}} = \dfrac{1.97 \times 10^{-3} \text{ mol}}{\text{98.5 mL }}\\\\\dfrac{n_{1}}{44.2} = 2.00 \times 10^{-5} \text{ mol}\\\\n_{1} = 44.2 \times 2.00 \times 10^{-5} \text{ mol} = 8.84 \times 10^{-4} \text{ mol}$

2. Calculate the initial mass of H₂S

$\text{Mass of H _{2} S} = 8.84 \times 10^{-4}\text{ mol H _{2} S} \times \dfrac{\text{34.08 g H _{2} S}}{\text{1 mol H _{2} S}} = \text{0.0301 g H _{2} S}\\\\\text{The container initially held }\boxed{\textbf{0.0301 g H _{2} S}}$