Physics

Physics

Problem

How much heat must be removed from 456 g of water at 25.0∘C25.0^{\circ}\text{C} to change it into ice at 10.0∘C10.0^{\circ}\text{C} ? The specific heat of ice is 2090 J/kg⋅K2090 \text{ J/kg} \cdot \text{K}, the latent heat of fusion of water is 33.5×104 J/kg33.5 \times 10^4 \text{ J/kg}, and the specific heat of water is 4186 J/kg⋅K4186 \text{ J/kg} \cdot \text{K}. (a) 105 kJ (b) 153 kJ (c) 57.3 kJ (d) 210 kJ
Intuitive explanation

This problem requires you to track energy removal through three distinct stages: cooling liquid water, freezing it at constant temperature, then cooling the resulting ice. The key is recognizing that phase changes happen at a fixed temperature and demand latent heat, while temperature changes within a single phase use specific heat. Calculate each stage's energy separately, then sum them—the total tells you how much heat must leave the system.

Intuitive explanation

This problem requires you to track energy removal through three distinct stages: cooling liquid water, freezing it at constant temperature, then cooling the resulting ice. The key is recognizing that phase changes happen at a fixed temperature and demand latent heat, while temperature changes within a single phase use specific heat. Calculate each stage's energy separately, then sum them—the total tells you how much heat must leave the system.

Browse the problem library