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Write the expression for the equilibrium constant for each of the following chem

ID: 504126 • Letter: W

Question

Write the expression for the equilibrium constant for each of the following chemical reactions. FE exam manual) 1) C_(s) + CO_2(g) doubleheadarrow CO_(g) 2) HNO_3 + H_2O doubleheadarrow H_3O^+ + NO^+_3 3) CaCO_3(s) doubleheadarrow CaO_(s) + CO_2 4) BaO_(s) + CO_2(g) doubleheadarrow BaCO_3(s) H_2PO^-_4 is in equilibrium with HPO^2-_4 in water: H_2PO^-_4 doubleheadarrow H^+ + HPO^2-_4 T = 25 degree C; [H_2PO^-_4] = 9.698 times 10^-5 M; [H^+] = [HPO^2 _4] = 3.018 times 10^6 M Using the extended Debye-Huckel approximation equation, calculate the following 1) when mu = 0 a) the activity coefficients for H_2PO^-_4, HPO^2-_4, and H^+ b) the equilibrium constant, Ka_2 c) the equilibrium constant corrected for ionic strength, Ka^_2 d) pKa_2 and pKa^c_2 2) when mu = 0.01 a) the activity coefficients for H_2PO^-_4, HPO^2-_4, and H^+ b) the equilibrium constant, Ka_2 c) the equilibrium constant corrected for ionic strength, Ka^c_2 d_ pKa_2 and pKa^c_2 key: Ka_2 = {H^+} {HPO^2+_}/{H_2PO^-_4} = gamma [H^+] gamma_H [HPO^2-_4]/gamma [H_2PO^-_4] [H^+] [HPO^2-_4]/[H_2PI^-] = (gamma_H_2PO^-_4)/(gamma_N) (gamma_HPO) Ka_2 = Ka^_2 - log Ka^_2 = pKa^_2

Explanation / Answer

1.

1)

C (s) + CO2 (g)    <——>       2CO(g)

Solid is not considered while writing Kc

So,

Kc = [CO]^2 / [CO2]

2)

HNO3 (aq) + H2O (l) <—> H3O+ (aq) + NO3- (aq)

Liquid is not considered while writing Kc

So,

Kc = [H3O+][NO3-] / [HNO3]

3)

CaCO3 (s) <—> CaO (s) + CO2 (g)

Kc = [CO2]

4)

BaO(s) + CO2 (g) <——> BaCO3 (s)

Kc = 1/[CO2]

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