Given the following thermochemical equation, what amount of energy is absorbed/given off when 255g of cu2o is reacted:

2cu2o(s)=4cu(s)+o2(g)

i just want to make sure i've set it up correctly. : )

A thermochemical equation must include the heat absorbed or given, so this question is incomplete.

So, I will work with the data of heat of formation from a table.

In this case, the table says:

4 Cu(s) + O2(g) > 2 Cu2O (s)    ΔHf = -333.4 kJ/mol

Our equation is in the inverse direction so ΔH'f = - ΔHf = 333.4 kJ/mol

Then, the heat of formation of our reaction is positive, which means that it is endothermic or absorb energy.

So, we know that the thermal equation is:

 2 Cu2O(s) + 333.4 kJ / mol ⇄ 4 Cu(s) + O2(g)

That is, 2 mol Cu2O(s) absorbs 2 * 333.4 kJ   of heat

Now calculate the number of moles of Cu2O in 255 g

You need the molar mass of Cu2O

Cu2O : 2 * 63.5 g/mol + 16 g/mol = 143 g/mol

# moles Cu2O = 255 g / 143 g /mol = 1.78 mol

 => ΔH = 1.78 mol * 333.4 kJ / mol = 593.5 kJ

593.5 kJ is absorbed

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