The oxidation of copper(i) oxide cu2o

The oxidation of copper(I) oxide, Cu2O(s), to copper(II) oxide, CuO(s), is an exothermic process, 2 CuO2(s) + 02(g) —> 4 CuO (s) The change in enthalpy upon reaction of 67.68 g of CuO (s) is -69.06 kJ
Calculate the work, w, and the energy change, delta Urxn, when 67.68 g of Cu2O (s) is oxidized at constant pressure of 1.00 bar and a constant temperature of 25 degree celcius? (the two answer must be in kJ)
I can’t get the right answer for some reason. Thank you. Show work please.

Answer

classmAte Date Page Mo 143-) PAo eik ニー587-18 /Tou The balanced chemical reaction is : 2Cu2O (s) + O2 (g) ————-> 4CuO (s) given that 67.68 g of Cu2O is reacted i.e. number of moles of Cu2O reacted = 67.68 g / 143.1 g mol-1 = 0.473 mol The stoichiometry of the balanced equation tells that each 2 mol of Cu2O reacts with 1 mole of O2 therefore; number of moles of O2 reacted = 0.473 / 2 = 0.24 mol Now, change in number of moles (Δn) of the compound in the gaseous state in the reaction is : Δn = nproducts (g) – nreactants(g)    = 0 – 0.24 = -0.24 and work done in chemical reaction given by w = – ΔnRT = – (-0.24 mol) * 8.314 J K-1 mol-1 * 298 K = 594.62 J ~= 0.594 kJ which is actually expansion (compression) work (-PΔV) positive sign indicates that work is done on the system. Also, ΔH = ΔU + Δ(PV) at constant pressure, ΔH = ΔU + PΔV => ΔU = ΔH – PΔV = -69.06 – 0.59

~= -69.65 kJ

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