Question

The volume occupied by 4.75 g of acetylene gas at 50 °C and 740 mmHg pressure is _______ L. (Rounded off to the nearest integer) [Given \( R = 0.0826 \, \text{L atm K}^{-1} \text{ mol}^{-1} \)]

Hint:

Ensure $P$ is in atmospheres (divide mmHg by 760) and $T$ is in Kelvin before using $R = 0.0821$ or $0.0826$.

Answer 1

Correct Answer: 5

Given:

Mass of acetylene (C₂H₂) = 4.75 g
Temperature = 50 °C
Pressure = 740 mmHg

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Step 1: Convert pressure into atm

P = 740 × (1 atm / 760 mmHg)

P = 0.9737 atm

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Step 2: Convert temperature into Kelvin

T = 50 + 273

T = 323 K

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Step 3: Calculate number of moles

Molar mass of C₂H₂ = 26.04 g mol⁻¹

n = 4.75 / 26.04

n = 0.182 mol

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Step 4: Apply ideal gas equation

PV = nRT

V = nRT / P

V = (0.182 × 0.0826 × 323) / 0.9737

V ≈ 5.097 L

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Step 5: Final approximation

V ≈ 5 L

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Final Answer:

Volume occupied by 4.75 g of acetylene gas,
5 L