The volume of 0.25 mol of a gas at 72.7 kPa and 15 °C is ________ m³. A)8.1 × 10^-5 B)1.2 × 10^-4 C)4.3 × 10^-4 D)8.2 × 10^-3 E)2.2 × 10^-1

Question

Quizplus · Accepted Answer

Use the ideal gas law:

PV = nRT

where P = 72.7 kPa, V is the volume we're solving for, n = 0.25 mol, R = 8.31 J/(mol K), and T = 15+273 = 288 K.

Rearranging for V:

V = (nRT)/P

Plugging in the values:

V = (0.25 mol)(8.31 J/(mol K))(288 K)/(72.7 kPa)

Convert kPa to Pa:

V = (0.25 mol)(8.31 J/(mol K))(288 K)/(72.7×10^3 Pa)

Simplify:

V = 0.0082 m^3 = 8.2 × 10^-3 m^3

Round to two significant figures:

V = 8.2 × 10^-3 m^3

The answer is therefore (D), 8.2 × 10^-3 m^3.

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