Question

Question 5 (1 point) The reaction of aluminum with oxygen is exothermic. The enthalpy of formation for aluminum oxide is - 1676 kJ/mol. How much heat will the combustion of 4.50 g of aluminum produce, in kJ? Include the proper sign for an exothermic or endothermic reaction.

Answer 1

4 Al + 3 O₂ = 2 Al₂ O₃

_or, Al + (3/4) O₂ = (2/4 ) Al₂ O₃

_{$\Delta H(f) = -1676 KJ/ mol$}

4.5 gm of Aluminium = 0.166 moles

1 mole aluminium produces = 0.5 moles of Al₂ O₃

0.166 molesaluminium produces = 0.5 X 0.166 = 0.083 moles of Al₂ O₃

To produce 1 moles of Al₂ O₃ = - 1676 kJ  

To produce 0.083 moles of Al₂ O₃ Heat released = - 1676 X 0.083 = -139.108 KJ