Concept Explanation: Cooling Effectiveness

When comparing which substance is more effective in cooling, we need to consider the latent heat of fusion and specific heat capacity. Cooling effectiveness depends on how much heat energy a substance can absorb when it comes in contact with a warmer object.

Step 1: Understand Heat Absorption

Ice at 0°C absorbs heat in two ways:

• First, it melts into water at 0°C by absorbing latent heat of fusion.
• Then, the resulting water can absorb more heat due to its specific heat capacity.

Water at 0°C only absorbs heat due to its specific heat capacity (no phase change).

Step 2: Compare Heat Absorption

For ice at 0°C to become water at 0°C, it absorbs latent heat:

where $L$ is latent heat of fusion (334 J/g for ice).

Then the water at 0°C can absorb additional heat:

where $c$ is specific heat capacity (4.18 J/g°C for water).

Step 3: Compare with Other Options

Water at 0°C only absorbs heat through specific heat capacity without any phase change, so it absorbs less heat than ice at the same temperature.

Gas at 0°C and water at 100°C are not relevant comparisons for effective cooling at lower temperatures.

Final Answer

Ice at 0°C is more effective in cooling because it absorbs additional latent heat during melting, which allows it to absorb more heat energy compared to water at the same temperature.

Related Topics

• Latent Heat of Fusion
• Specific Heat Capacity
• Phase Changes
• Heat Transfer

Important Formulae

Heat absorbed during phase change (melting):

Heat absorbed without phase change:

where:
$Q$ = heat energy (J)
$m$ = mass (g)
$L$ = latent heat of fusion (334 J/g for ice)
$c$ = specific heat capacity (4.18 J/g°C for water)
$\mathrm{\Delta T}$ = temperature change (°C)