Question

answer #63 by using #61

63) Use standard free energies of formation to calculate ΔG° at 25°C for each reaction in Problem 61. How do the values of AG° calcu- lated this way compare to those calculated from ΔΗ' and AS? Which of the two methods could be used to determine how ΔG changes with temperature? İN or each reaction, calculate Δ Hon, Δ-mn, and ΔGon at 25°C and state whether the reaction is spontaneous. If the reaction is not spontaneous, would a change in temperature make it spontaneous? If so, should the temperature be raised or lowered from 25°C? a. N2O4(g) 2 NO2(g) b. NH,Cl(s) HCI(g) +NH,(g) c. 3 H2(g) + Fe203(s)2 Fe(s) +3 H2O(g) d. N2(g) + 3 H2 2NH,(g) bl

Answer 1

Here the standard free energy change, standard enthalpy change, and standard entropy change is calculated and the final answer is given.

standard values of reactants are subtracted from the products

After that for each reaction, the Gibbs free energy change is calculated at 298 K

a)

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b)

2 5 △H。.re. ‘ ..=. 174.02. IcJ. Scanned with CamScanner

c)

(S s Scanned with CamScanner

d)

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Only Reaction d is spontaneous as the free energy change is -ve

all other reactions are nonspontaneous(a,b,c)

If we increase the temperature in a,b,c the process become spontaneous since all the cases standard free energy change is +ve.

To find the change in free energy with temperature is the change in enthalpy and entropy at a particular temperature should be found experimentally and can apply in Gibb's-Helmoltz equation.