# carbon dioxide dissolves in water to form carbonic acid. Estimate the thermodynamic equilibrium constanst (K) for this reaction (delta Gf values: H2CO3= - 616.1, H2O= - 237.1, CO2= - 394.4) .

Carbonic acid then ionizes in water (Ka1= 4.5 x 10^-7). Ignoring Ka2, estimate (K) for the overall process by which CO2 and H2O form H and HCO3.

What is the pressure of CO2 in equilibrium with carbonated water at 25 C and PH= 4.78?

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1. CO2 + H2O ==> H2CO3
dGrxn = (dG products) - (dG reactants)
Then dG = -RTlnK
Solve for K.

Then H2CO3 ==> H^+ + HCO3^-
k1 = 4.5E-7
For the two reactions together you have
CO2 + H2O ==>H^+ + HCO3^- and Keq = k1K.

Finally, convert pH 4.78 to H^+, substitute into the equation (HCO3^- = H^+ too) and solve for partial pressure of CO2.

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2. Thank you so much for replying, but I can't understand how to solve for partial pressure of CO2, when I get the [H^+] from PH then how to solve for partial pressure of CO2?

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3. Thanks a lot, I got it.

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4. I kept record of all IP addresses and they will be reported to UCI undergrad offices.

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5. @Amanda lolololol

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6. @Amanda, k

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7. Thanks!

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8. I still don't understand how to find the partial pressure of CO2. I've got the H+ concentration but I'm stuck at that step.

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9. the partial pressure is determine by
K= [hc03][h]/pressure

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10. So the pressure =.202 atm

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11. where do you get the T in the first one?

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12. I don't understand how to find the partial pressure can someone explain it to me please I have a homework due tonight that is similar to this

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