calculate the equilibrium constants at 25?C for each reaction: The answer for A

Question

calculate the equilibrium constants at 25?C for each reaction:

The answer for A is 1.5E90 The answer for B is 1.9E-31 If someone can explain how to find the correct answers, I would appreciate it.

Part A 2 CO(g) + O2 (g) 2 CO2 (g) Express your answer using two significant figures. K= 1.5×1090 Submit My Answers Give Up All attempts used, correct answer displayed Part B N2 (g) + O2 (g) 2 NO (g) Express your answer using two significant figures. K-1.9x10-31 Submit My Answers Give Up Answer Requested

Explanation / Answer

Equilibrium constant (K) and standard Gibbs free energy change (G0rxn) for the reaction are related as,

(G0rxn) = –RT ln(K)

Using R = 8.314 J.K–1.mol–1 and T = 25 oC = 298.15 K

(G0rxn) = –8.314 x 298.15 ln(K)

(G0rxn) = – 2.48 x 103 ln(K)……………(1)

For given reactions we need to find (G0rxn) using Standard Gibbs energies (G0f)) of formations of species involved in reaction concerned.

Formula,

G0rxn = G0f (producs) – G0f (Reactant)

Part-A)

G0rxn = 2 x G0f (CO2) – [G0(O2) + 2 x G0CO]

G0rxn = 2 x ( –394.39) – [0+(2 x –137.16)]

G0rxn = –514.46 kJ/mol

G0rxn = –514460 J/mol

Now using above equation (1)

(G0rxn) = – 2.48 x 103 ln(K)

–514460 = – 2.48 x 103 ln(K)

ln(K) = –514460/(– 2.48 x 103)

ln(K) = 207.44

K = e207.44

K = 1.2 x 1090

Hence the equilibrium constant value for given reaction.

=======================================

Part-B)

Given chemical transformation,

N2 (g) + O2 (g) < ------> 2NO (g)

Let us find,

G0rxn = 2 x G0f (NO) – [G0 (O2) + G0N2]

G0rxn = 2 x (87.60) – [0+0]

G0rxn = 175.2 kJ/mol

G0rxn = 175200 J/mol

Using eq. (1)

(G0rxn) = – 2.48 x 103 ln(K)

175200 = – 2.48 x 103 ln(K)

ln(K) = 175200/(– 2.48 x 103)

ln(K) = –70.65

K = e–70.65

K = 2.1 x 10–31

Hence the equilibrium constant value for given reaction.

=====================XXXXXXXXXXXXXX==============================

I used standard Gibbs energies of formation of species concenrned from literature.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.