uestion 4 of 25 Roberts & Company Publishers Organic Chemistry presented by Sapl

Question

uestion 4 of 25 Roberts & Company Publishers Organic Chemistry presented by Sapling Loaming A reaction Alag) Blaq Caal has a standard free-energy change of-542 kJmol at 25 C. What are the ofA B, and at the beginning of the reaction, their concentrations are 0.30 M. 0.40 M, and 0M, respectively? Number [A] (B)- M Tools How would your answers above change the reaction had a standard free-energy cha x 10 kJ/mol? O All concentrations would be lower. O There would be less A and B but more C. O There would be no change to the answers. O There would be more A and B but less C. O All concentrations would be higher. O Previous e Give Up s view Solution Check o Next Exit Answer berms of use JBC SCC-61

Explanation / Answer

First, we need K

from

dG = -RT*ln(K)

solve for it

K = exp(-dG/(RT))

k = exp(5420/(8.314*298))

k = 8.91402

so.

K = [C]/([A][B])

initially

[A] = 0.3

[B] = 0.4

[C] = 0

in equlibrium

[A] = 0.3 - x

[B] = 0.4 - x

[C] = 0 + x

substitute

8.91402 = x/ (0.3-x)(0.4-x)

(0.3*0.4 - 0.7x + x^2) = 0.112x

x^2 -(0.7+0.112)x + 0.12 = 0

x = 0.194

[A] = 0.3 - 0.194 = 0.106

[B] = 0.4 - 0.194 = 0.206

[C] = 0 + 0.194

Clearly, thee will be more C, since the K favours production

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