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Specific heat capacity and latent heat questions

Calculate heating energy, temperature rise and changes of state; analyse electrical heating and stated energy losses.

Practise

Energy for melting

1 kg of a solid is already at its melting temperature. Its specific latent heat of fusion is 200000 J kg⁻¹. Find the energy needed to melt it completely at constant temperature. Give your answer to 3 significant figures.

Treat the given values as exact unless an uncertainty is stated.

Use decimals or e notation, e.g. 4.2e-3. Enter the unit separately.

Hint

Use E = mL for the change of state.

Worked solution
  1. E = 1 × 200000 J.
  2. Answer: 2.00 × 105 J (3 significant figures).
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Question type: Mixed practice
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Foundation and Higher: this set covers content common to both tiers. Some calculations need several steps.

Heating and changes of state

Use E = mcΔθ when temperature changes without a change of state. Use E = mL for a change of state at constant temperature. Specific heat capacity is measured in J kg⁻¹ °C⁻¹; specific latent heat in J kg⁻¹. Electrical input Pt may include energy transferred to the surroundings and apparatus. Only treat it as energy gained by the sample when the question states that assumption.

Work through the practical method and sample results

GCSE scope

AQA 8463: 4.1.1.3; 4.3.2.2–3; required practical 1 (selected); OCR Gateway J249: P1.2d–f; PM1.2i–ii; PAG P5 (selected). Tasks cover the selected skills listed above.

AQA specification · OCR Gateway specification