Needed Information:
* Mass of the substance (m): This is the amount of material undergoing the phase change.
* Heat of fusion (ΔHfus): This is a specific property of the substance and represents the amount of energy required to melt one gram (or one mole) of the substance at its melting point.
* Melting point (Tfus): While you don't need the exact temperature for the calculation itself, you need to know if the substance is actually at its melting point for the calculation to be valid.
Information Not Needed:
* Specific heat capacity (c): This is the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius. Specific heat is relevant for temperature changes within a phase, but not for phase changes themselves.
* Initial temperature (Ti): The initial temperature is irrelevant as long as the substance is at its melting point. The heat of fusion already accounts for the energy required to change the state.
The Formula:
The heat absorbed (Q) during melting can be calculated using the following formula:
Q = m * ΔHfus
Example:
Let's say you want to calculate the heat absorbed when 10 grams of ice melts. The heat of fusion of water is 334 J/g.
Q = (10 g) * (334 J/g) = 3340 J
So, 3340 Joules of heat are absorbed to melt 10 grams of ice.
