A 2.0‑kg block of ice at 0 °C is placed in a 500‑g metal container that is initially at 20 °C. The ice melts and the final temperature of the system is 10 °C. Explain, using the conservation of energy, how the energy transferred from the metal to the ice is distributed between the melting of the ice and the warming of the melted water.

The metal loses thermal energy, which is transferred to the ice. Part of this energy is used to break the hydrogen bonds between water molecules, i.e. the latent heat of fusion, allowing the ice to change state to liquid water. The remaining energy increases the kinetic energy of the water molecules, raising the temperature from 0 °C to 10 °C. The total energy lost by the metal equals the sum of the energy used for melting and the energy used for heating the water, illustrating conservation of energy.

Cause lens: Name the cause, then state the effect on particles, pressure, density, or energy. This question asks: A 2.0‑kg block of ice at 0 °C is placed in a 500‑g metal container that is initially at 20 °C. The ice melts and the final temperature of the system is 10 °C. Explain, using the conservation of energy, how the energy transferred from the metal to the ice is distributed between the melting of the ice and the warming of the melted water. The correct response is The metal loses thermal energy, which is transferred to the ice. Part of this energy is used to break the hydrogen bonds between water molecules, i.e. the latent heat of fusion, allowing the ice to change state to liquid water. The remaining energy increases the kinetic energy of the water molecules, raising the temperature from 0 °C to 10 °C. The total energy lost by the metal equals the sum of the energy used for melting and the energy used for heating the water, illustrating conservation of energy., because changes of state are explained by particle energy and arrangement. In Internal energy, the marking point should connect directly to apply the conservation of energy idea to heating and changes of state. 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 268 is distinct because it uses this exact question context and the cause lens rather than a generic particle-model sentence.