A kilogram of aluminum metal and a kilogram of water are each warmed to 75 °C and placed in two identical insulated containers. One hour later, the two containers are opened and the temperature of each substance is measured. The aluminum has cooled to 35 °C, while the water has cooled only to 66 °C. Explain this difference.

Key Concepts

Specific Heat Capacity

Specific heat capacity is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. Different materials have different specific heat capacities, which affects how they absorb and release heat. Water has a high specific heat capacity (4.18 J/g°C), meaning it can absorb a lot of heat without a significant change in temperature, while aluminum has a lower specific heat capacity (0.897 J/g°C), leading to a quicker temperature change.

Thermal Equilibrium

Thermal equilibrium occurs when two substances at different temperatures are in contact, and heat flows from the hotter substance to the cooler one until they reach the same temperature. In this scenario, the aluminum and water started at the same temperature but have different cooling rates due to their specific heat capacities, resulting in different final temperatures after one hour.

Insulation and Heat Loss

Insulation refers to materials that reduce the rate of heat transfer between substances. In this experiment, the insulated containers minimize heat loss to the environment, allowing for a more accurate comparison of how the two substances cool. The difference in final temperatures is primarily due to the inherent properties of aluminum and water, rather than external heat loss.