Question

Question 1

A 350 mL glass bulb is filled with an unknown gas with a mass of 0.225 g fills, a pressure of 733 mmHg and a temperature of 22 °C. Is this gas argon (Ar), methane
X (CH4), nitrogen monoxide (NO), or carbon monoxide (CO)?

Answer 1

Methane

Step-by-step explanation:

Step 1: Convert the volume to L

We will use the relationship 1 L = 1000 mL.

350 mL × 1 L/1000 mL = 0.350 L

Step 2: Convert the pressure to atm

We will use the relationship 1 atm = 760 mmHg.

733 mmHg × 1 atm/760 mmHg = 0.964 atm

Step 3: Convert the temperature to Kelvin

We will use the following expression.

K = °C + 273.15 = 22 + 273.15 = 295 K

Step 4: Calculate the moles of the gas

We will use the ideal gas equation

P × V = n × R ×T

n = P × V/R ×T

n = 0.964 atm × 0.350 L/0.0821 atm.L/mol.K ×295 K

n = 0.0139 mol

Step 5: Calculate the molar mass of the gas

0.0139 moles have a mass of 0.225 g. The molar mass of the gas is:

0.225 g / 0.0139 mol = 16.2 g/mol

From the options, methane is the gas with a molar mass of about 16.2 g/mol.