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

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom. 

Answerδh > 0explanationc₆h₆  (s)  → c₆h₆ (l)if you are changing it from a solid to a liquid, you are pretty much melting the solid. this requires heat energy. therefore, the reaction is endothermic (takes in energy); the system enthalpy increases as the reaction proceeds: δh > 0.