Thermal expansion of liquids and gases — KCSE Physics

KCSE Physics · 108 practice questions · 11 syllabus objectives

37 easy35 medium36 hard

What You'll Learn

Key learning outcomes for this topic, aligned to the KNEC KCSE syllabus.

Define an ideal gas and explain why absolute zero is practically unattainable

Apply Boyle's law (P₁V₁ = P₂V₂) and Charles' law (V₁/T₁ = V₂/T₂) to solve gas problems

Apply the combined gas law (P₁V₁/T₁ = P₂V₂/T₂) to calculate changes in pressure, volume or temperature

Explain anomalous expansion of water and state its importance in aquatic ecosystems

Explain why liquids expand more than solids and describe the initial drop in water level when a flask is heated

Describe the anomalous expansion of water, sketch the density-temperature graph and state its significance

State properties of thermometric liquids and describe the construction of liquid-in-glass thermometers

Describe experiments to demonstrate expansion of air and gases

Compare mercury and alcohol as thermometric liquids and describe the clinical thermometer

State Charles’s law and define absolute zero; solve gas expansion problems at constant pressure

Thermal expansion of liquids and gases

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easySHORT ANSWER3 marks

Identify three characteristics of thermometric liquids used in liquid-in-glass thermometers. (3 marks)

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Part (a) — 3 marks

Thermometric liquids should have a high thermal expansion coefficient to ensure noticeable movement (1 mk)

They must remain in a liquid state over a wide temperature range to provide accurate readings (1 mk)

The liquid should have a uniform and predictable expansion characteristics for reliable measurements (1 mk)

easySHORT ANSWER2 marks

Name two characteristics of water that demonstrate its anomalous expansion when it cools from 4°C to 0°C. (2 marks)

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Part (a) — 2 marks

Water expands upon cooling from 4°C to 0°C, resulting in a decrease in density (1 mk)

Ice forms on the surface while water remains liquid below, allowing aquatic life to survive (1 mk)

easySHORT ANSWER2 marks

State the reason for the initial drop in water level in a flask when heated. (2 marks)

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Part (a) — 2 marks

Water expands upon heating, but initially, the expansion is not enough to overcome the confined volume (1 mk)

The water may initially lose some volume due to thermal expansion of the flask material (1 mk)

Explain why liquids expand more than solids when heated. (3 marks)

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