Question

Calculate the molar mass of a gaseous substance if 0.125 g of the gas occupies 93.3 mL at STP.

Answer 1

Answer:

30.0g/mol

Explanation:

Step 1: Given data

• Mass of the gas: 0.125 g

• Pressure (P): 1 atm (standard pressure)

• Temperature (T): 273.15 K (standard temperature)

• Volume (V): 93.3 mL

Step 2: Calculate the moles of the gas

We will use the ideal gas equation.

$P \times V = n \times R \times T\\n = \frac{P \times V}{R \times T} = \frac{1atm \times 0.0933L}{\frac{0.0821atm.L}{mol.K} \times 273.15K} = 4.16 \times 10^{-3} mol$

Step 3: Calculate the molar mass of the gas

4.16 × 10⁻³ moles correspond to a mass of 0.125 g. The molar mass of the gas is:

$\frac{0.125g}{4.16 \times 10^{-3} mol} =30.0g/mol$