The enthalpy of fusion of aluminum is 10.7 kJ/mol. How many grams of aluminum can be melted by adding 81.4 kJ of energy to the metal at its melting point

The correct answer is  205.4 g Al

Explanation:

Given the enthalpy of fusion (ΔHf) of aluminum (Al), the amount of heat required to melt the substance is calculated as follows:

heat = ΔHf x moles Al

We have the following data:

ΔHf = 10.7 kJ/mol

heat= 81.4 kJ

So, we calculate the moles of Al we can melt:

moles =heat/ΔHf= 81.4 kJ/(10.7 kJ/mol)= 7.61 moles

The relation between moles and grams of Al is given by the molar mass of Al (27 g/mol). Thus, we multiply the moles of Al by the molar mass to calculate the grams of Al we can melt:

grams = 7.61 moles x 27 g/mol = 205.4 g

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