Why does the temperature of a sample not immediately increase as energy is added after ice begins to melt?

• A. The added energy is used to break hydrogen bonds during the phase change rather than increasing kinetic energy.
• B. The melting process releases energy, which offsets the added energy.
• C. The energy is absorbed by the surroundings, preventing temperature increase.
• D. The heat capacity of water is lower than that of ice, so temperature remains constant.

Answer: (A)

Verified step by step guidance

1. Understand that temperature measures the average kinetic energy of particles in a substance.
2. Recognize that during a phase change, such as melting, the energy added to the system is used to overcome intermolecular forces (like hydrogen bonds) rather than increasing kinetic energy.
3. Recall that breaking hydrogen bonds requires energy input called the latent heat of fusion, which does not raise the temperature but changes the phase from solid to liquid.
4. Note that because the energy goes into changing the phase, the temperature remains constant until the entire sample has melted.
5. Conclude that the temperature does not immediately increase after ice begins to melt because the added energy is consumed in breaking hydrogen bonds, not in increasing particle motion.