Question detail
Calculate the energy required to freeze 1.5 kg of water at 0°C. The specific latent heat of fusion for water is 334,000 J/kg (Changes of state and specific latent heat) (Changes of state and specific latent heat; particle reasoning focus: Calculate energy transferred during melting, freezing, boiling or condensing when mass and specific latent heat are known) (Changes of state and specific latent heat; particle reasoning focus: Calculate energy transferred during melting, freezing, boiling or condensing when mass and specific latent heat are known)
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Internal energy and energy transfers
Question
- A. 501,000 J
- B. This confuses specific latent heat with a different particle-model idea in Internal energy and energy transfers.
- C. This gives a vague particle statement without answering the particle reasoning focus.
- D. This reverses the cause and effect for Changes of state and specific latent heat.
Answer
The correct answer is 501,000 J.
Explanation
Unit lens: Check the units before giving the final statement so the physics quantity is not swapped. This question asks: Calculate the energy required to freeze 1.5 kg of water at 0°C. The specific latent heat of fusion for water is 334,000 J/kg (Changes of state and specific latent heat) (Changes of state and specific latent heat; particle reasoning focus: Calculate energy transferred during melting, freezing, boiling or condensing when mass and specific latent heat are known) (Changes of state and specific latent heat; particle reasoning focus: Calculate energy transferred during melting, freezing, boiling or condensing when mass and specific latent heat are known). The correct response is 501,000 J, because density links mass and volume, so the answer must preserve which quantity is being calculated. In Changes of state and specific latent heat, the marking point should connect directly to calculate energy transferred during melting, freezing, boiling or condensing when mass and specific latent heat are known. If the question includes values, the working must keep the appropriate unit and operation; if it is an explanation, it must name the relevant particle behaviour or energy change. This item belongs to Internal energy and energy transfers, so avoid answers that switch to a different quantity, confuse heat with temperature, or describe gas pressure without collisions when collisions are the reason. Checkpoint 397 is distinct because it uses this exact question context and the unit lens rather than a generic particle-model sentence.
Common mistake
Confusing Energy Transfer with Temperature Change
Students often think that energy transfer during a change of state affects temperature, leading to confusion about why temperature remains constant during melting or boiling.
Emphasize that energy transferred during a change of state changes the potential energy of particles, not their average kinetic energy, which is related to temperature.
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