7. What quantity of energy in kJ must be absorbed by 6.47 mol of acetic acid acid, C₂H4O2, to melt it at its melting point,
16.7 °C? The molar enthalpy of fusion for acetic acid is 11.54 kJ/mol



Answer :

To calculate the quantity of energy required to melt 6.47 moles of acetic acid at its melting point, we can use the molar enthalpy of fusion. The molar enthalpy of fusion is the amount of energy required to melt 1 mole of a substance at its melting point. Given: - Number of moles of acetic acid (\(n\)) = 6.47 mol - Molar enthalpy of fusion (\(\Delta H_{fus}\)) = 11.54 kJ/mol The energy (\(Q\)) absorbed to melt the acetic acid can be calculated using the formula: \[Q = n \times \Delta H_{fus}\] Plugging in the given values: \[Q = 6.47 \, \text{mol} \times 11.54 \, \text{kJ/mol}\] Now, multiply the number of moles by the molar enthalpy of fusion: \[Q = 74.6768 \, \text{kJ}\] Therefore, to melt 6.47 moles of acetic acid at its melting point, 74.68 kJ of energy must be absorbed (rounded to two decimal places).