Question

How many kJ of heat are needed to completely melt 17.3 g of H2O, given that the water is at its melting point? The heat of fusion for water is 6.02 kJ/mole.

Answer 1

Answer: Heat required for 17.3 g of water to completely melt will be 5.785 kJ.

Explanation: Heat of fusion is defined as the amount of heat require to change the state from solid to liquid for 1 mole of solid at its melting point. It is expressed as $\Delta H_{fusion}$

We are given 17.3 grams of water. So, to convert it into moles, we use the formula:

$Moles=\frac{\text{Given mass}}{\text{molar mass}}$

Molar mass of water = 18g/mol

Putting values in above equation, we get:

$Moles=\frac{17.3g}{18g/mol}$

Moles of water = 0.961 moles

For 1 mole of water, heat of fusion is 6.02kJ/mol

So, for 0.961 moles of water, heat of fusion will be = (0.961 moles × 6.02 kJ/mol) = 5.785 kJ