Explain why the temperature of a substance remains constant during a change of state, even though energy is being transferred.

During a change of state, the energy transferred is used to change the potential energy of the particles rather than their average kinetic energy. This means that while energy is added or removed, the temperature does not change until the state change is complete.

Particle lens: Describe arrangement, motion, spacing, collisions, or energy changes only when they are relevant here. This question asks: Explain why the temperature of a substance remains constant during a change of state, even though energy is being transferred. The correct response is During a change of state, the energy transferred is used to change the potential energy of the particles rather than their average kinetic energy. This means that while energy is added or removed, the temperature does not change until the state change is complete., 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 recall and apply the equation energy for a change of state = mass x specific latent heat. 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 384 is distinct because it uses this exact question context and the particle lens rather than a generic particle-model sentence.