eral Chemistry 4th Edition Map niversity Science Books presertiad bw Sapling Lea
ID: 540078 • Letter: E
Question
eral Chemistry 4th Edition Map niversity Science Books presertiad bw Sapling Learring The oxidation of copperi) oxide, CuzO(s), to copper(l) oxide, CuO(s), is an exothermic process. The change in enthalpy upon reaction of 84.90 g of CuzO(s) is -86.63 KJ Calculate the work, w and energy change, AUrn, when 84.90 g of Cu0(s) is oxidized at a constant pressure of 1.00 bar and a constant temperature of 25 . Number Number Note that AEs is sometimes used LIas the symbol for energy change kJ instead of AUn:Explanation / Answer
2Cu2O(S) + O2(g) ----> 4 CuO(s)
Dn = np-nR = -1
No of mol of Cu2O = W/MWT = 84.9/145.107 = 0.585 mol
from equation , 2 mol 2Cu2O = 1 mol O2
if 0.585 mol Cu2O reacted, No of mol of O2 reacted = 0.585*1/2 = 0.2925 mol
so that, Dn of reaction = -0.2925
DH = DU + DnRT
w = -PDV
from ideal gas equation , PDV = DnRT
w = - DnRT
Dn = -0.2925 , R = 8.314 j.k-1.mol-1 , T = 25 c = 298 k
w = -(-0.2925)*8.314*298
= 724.69 joule
= 0.725 kj
DUrxn = DH-DnRT
= -86.63+0.725
= -85.905 kj
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