Answer to Question #168035 in Chemistry for Ava Brooke

Question

How much energy in kJ is released when 10.06 g of aluminum react with an excess of copper oxide?

3 CuO + 2 Al -> 3 Cu + Al₂O₃  

△ H

 = 1190 kJ/mol

Answer 1

Solution:

The balanced thermochemical equation:

3CuO + 2Al → 3Cu + Al₂O₃, △H = 1190 kJ/mol

The equivalences for this thermochemical equation are:

3 mol CuO ⇔ 2 mol Al ⇔ 3 mol Cu ⇔ 1 mol Al₂O₃ ⇔ +1190 kJ

Convert the amount of aluminum (Al) to moles:

10.06 g Al × ( 1 mol Al / 26.981 g Al) = 0.37285 mol Al

Using the thermochemical equation to determine the energy change:

0.37285 mol Al × (+1190 kJ / 2 mol Al) = +221.85 kJ

Answer: +221.85 kJ