# How many kilojoules are required to melt 24 g of ice at 100 degrees Celsius?

## Question:

How many kilojoules are required to melt 24 g of ice at 100 degrees Celsius?

## Heat of Fusion:

The latent heat of fusion is the enthalpy required to convert a substance from solid to liquid or liquid to solid. For water, this energy is less than the latent heat of of vaporization (the enthalpy required to convert a substance from gas to liquid or vice versa) because of the strong hydrogen bonds in water needed to be broken when transitioning from a liquid to a gas.

## Answer and Explanation:

The equation used to calculate the energy of vaporization {eq}Q_{fus} {/eq} to undergo a phase change between a solid to a liquid is {eq}Q_{fus}=m\cdot\Delta H_{fus} {/eq} where {eq}m {/eq} is the mass of the substance and {eq}\Delta H_{fus} {/eq} is the latent heat of fusion, which for water, is 334 J/g at 100 degrees Celsius. As can be seen from the equation the temperature does not affect the equation. Therefore, the amount of energy required to melt 24 g of ice at 100 degrees Celsius is

{eq}Q_{fus} = \left(24g\right)\cdot\left(334\frac{J}{g}\right) = 8.0\times 10^3 J = 8.0kJ {/eq}.

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