Thursday
March 23, 2017

Post a New Question

Posted by on Monday, August 8, 2011 at 5:20pm.

A) Calculate the hydrogen-ion concentration of a 5.45*10^-4 M H2CO3, solution, noting that Ka is bigger than Kb.
B)What is the concentration of CO3^2-?

after finding the concentration to A), do i use that concentration (M) as the initial M for CO3^2-?
thanks in advnace

  • chemistry - , Monday, August 8, 2011 at 8:00pm

    To be honest I don't understand the caution in the problem. I also think the concn of the H2CO3 is so low that it may cause problems but it didn't have that much effect on the final calculation.
    H2CO3 ==> H^+ + HCO3^-
    Set up an ICE chart, use k1 ONLY, (just think of it as a monoprotic acid and work the H^+ that way). It PROBABLY is a good idea to include the quadratic eqution and solve that.
    [(H^+)(HCO3^-)/(H2CO3-(H^+)] = k1 which becomes
    [(x)(x)/(H2CO3-x)] = k1.

    For part b, the trick here is to think of this diprotic acid as a monoprotic acid. Then (H^+) = (HCO3^-)
    Now look at k2 expression.
    k2 = (H^+)(CO3^2-)/(HCO3^-)
    BUT, if (H^+) = (HCO3^-) then (H^+) in the numerator cancels with (HCO3^-) in the denominator and k2 = (CO3^2-)

Answer This Question

First Name:
School Subject:
Answer:

Related Questions

More Related Questions

Post a New Question