How can I calculate the enthalpy of fusion?

Calculating the enthalpy of fusion involves understanding the energy required to change a substance from solid to liquid at its melting point. Here’s a straightforward approach to find this value:

Required Information

To calculate the enthalpy of fusion, you need:

• The mass of the substance (in grams)
• The heat absorbed during the phase change (in joules or calories)

Formula

The enthalpy of fusion (\( \Delta H_f \)) can be calculated using the formula:

\( \Delta H_f = \frac{q}{m} \)

Where:

• q = heat absorbed (in joules or calories)
• m = mass of the substance (in grams)

Steps to Calculate

1. Measure the mass of the solid substance.
2. Heat the substance until it completely melts, and measure the total heat absorbed.
3. Plug the values into the formula to find the enthalpy of fusion.

Example Calculation

If you have 50 grams of ice that absorbs 3340 joules of heat to melt, the calculation would be:

\( \Delta H_f = \frac{3340 \text{ J}}{50 \text{ g}} = 66.8 \text{ J/g} \)

This means the enthalpy of fusion for ice is 66.8 J/g. This value indicates how much energy is needed to melt one gram of ice at its melting point.