Final answer:
The heat energy released when 14.2 grams of liquid mercury solidifies at its melting point is calculated using the moles of mercury and the molar heat of fusion, resulting in -0.1621 kJ.
Step-by-step explanation:
To calculate the heat energy released when 14.2 grams of liquid mercury is converted to solid mercury at its melting point, we need to know the molar heat of fusion (or solidification) for mercury. The molar heat of fusion is the amount of heat energy required to melt or freeze one mole of a substance without changing its temperature. For mercury, this value is 2.29 kJ/mol at its melting point.
First, we convert the mass of mercury to moles using its molar mass (200.59 g/mol).
Number of moles of mercury = 14.2 g / 200.59 g/mol = 0.0708 mol.
Then, we use the molar heat of fusion to find the heat energy:
Heat energy (Q) = Number of moles × Molar heat of fusion
Q = 0.0708 mol × 2.29 kJ/mol = 0.1621 kJ
Since the substance is freezing, the heat is being released, and thus our answer would be -0.1621 kJ (negative, indicating an exothermic process).