Domestic LPG is stored and delivered in cylinders as a liquid. Estimate the density of liquid LPG relative to water (1 g/cc): is it about one fourth, one third, half, or one eighth that of water?

Difficulty: Easy

Correct Answer: Half

Explanation:

Introduction / Context:Liquefied petroleum gas (LPG) in household cylinders exists largely as liquid under pressure. Knowing its density relative to water helps in safe handling, storage design, and fill calculations.Given Data / Assumptions:

  • Water density ≈ 1 g/cc at ambient conditions.
  • LPG composition: mixtures of propane and butane.
  • Question seeks an approximate fraction of water density.

Concept / Approach:Typical liquid-phase densities: propane ≈ 0.50–0.52 g/cc (ambient), butane ≈ 0.57–0.60 g/cc. Commercial LPG blends fall near the middle of this range depending on season and locale, roughly about half the density of water.Step-by-Step Solution:

1) Recall representative liquid densities for propane/butane.2) Average for blended LPG lies around 0.50–0.58 g/cc.3) Therefore, choose “Half” as the best approximation versus 1 g/cc for water.

Verification / Alternative check:Cylinder mass/volume calculations used by distributors align with ~0.5–0.55 g/cc, validating the “half” estimate.

Why Other Options Are Wrong:

One fourth / one eighth: far too low for typical LPG blends.One third: still low versus common blend densities (closer to 0.5).

Common Pitfalls:Confusing LPG vapour density with liquid density; vapour density is relative to air, not water.

Final Answer:Half

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