K 1of 17 any household cleaning products contain oxalic acid, H2C204, a diprotic
ID: 1026402 • Letter: K
Question
K 1of 17 any household cleaning products contain oxalic acid, H2C204, a diprotic acid with the following ssociation constants Kal-5.9 10 2, Ka2 = 6.4x 10-5 Part A Calculate the equilibrium concentration of H,0t in a 0 20 M solution of oxalic acid Express your answer to two significant figures and include the appropriate units , View Available Hint(s) H0 0083 M Correct The fact that the initial acid concentration was not a thousand times bigger than the acid- dissociation constant was a clue that we would have to solve the full quadratic equation Now that we know the value of z (0.083 M), we can verify that [Hs O] is more than 5 percent of the initial concentration, and therefore not negligible compared to 0.20 M Part B Calculate the equilibrium concentration of C2O4 in a 0 20 M solution of oxalic acid Express your answer to two significant figures and include the appropriate units. View Available Hint(s) HA 02 0 Value UnitsExplanation / Answer
H2C2O4(aq) + H2O(l) ---------> H3O^+(aq) + HC2O4^- (aq)
I 0.2 0 0
C -x +x +x
E 0.2-x +x +x
Ka1 = [H^+][HC2O4^-]/[H2C2O4]
5.9*10^-2 = x*x/0.2-x
5.9*10^-2 *(0.2-x) = x^2
x = 0.083
[H3O^+] = x= 0.083M
[HC2O4^-] = x= 0.083M
HC2O4^- + H2O -----------------> H3O^+ (aq) + C2O4^2- (aq)
Ka2 = [H3O^+][C2O4^2-]/[HC2O4^-]
6.4*10^-5 = 0.083*[C2O4^2-]/0.083
[C2O4^2-] = 6.4*10^-5 M
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