Please show all work and explain. Thank you Sapling Learning Carbon dioxide diss

Question

Please show all work and explain. Thank you

Sapling Learning Carbon dioxide dissolves in water to form carbonic acid. Estimate the thermodynamic equilibrium constant for this reaction using the AGf values Substance AG (kJ/mol) in the table. H2CO3 (aq) -616.1 -237.1 H20 Number CO2(g) -394.4 Carbonic acid then ionizes in water (Kem 4.5x 10 7). Ignoring Ka2, estimate Kfor the overall process by which CO2 and H2O form H and HCO3 Number What is the pressure of CO2 in equilibrium with carbonated water at 25 C and pHE 4.60? Number atm CO,

Explanation / Answer

CO2 + H2O <==> H2CO3

dGof = dGof(products) - dGof(reactants)

         = -616.1 - (-237.1 - 394.1)

         = 15.1 kJ

Using,

dGo = -RTlnK

15100 = -8.314 x 298 lnK

K = 2.25 x 10^-3

IInd ionization reaction : H2CO3 <==> H+ + HCO3-

add the two equations,

net reaction,

CO2 + H2O <=> H+ + HCO3-

Overall K = 4.5 x 10^-7 x 2.25 x 10^-3 = 1.01 x 10^-9

pressure of pCO2 at pH = 4.60

pH = -log[H+] = 4.60

[H+] = 2.5 x 10^-5 M = [HCO3-]

At equilibrium.

K = 1.01 x 10^-9 = [H+][HCO3-]/pCO2

1.01x 10^-9 = (2.5 x 10^-5)^2/pCO2

pCO2 = 0.62 atm

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