Question

Calcualte `[OH^(-)]` & `[H_(2)C_(2)O_(4)]` in a `0.005M Na_(2)C_(2)O_(4)` solution.Given :`K_(a_(1))&K_(a_(2))` for oxalic acid are `5.6xx10^(-2)`& `5.4xx10^(-5)`Take `sqrt((1)/(108))=0.096`
A. `[OH^(-)]=9.6xx10^(-7)M`
B. `[H_(2)C_(2)O_(4)]=(5)/(28)xx10^(-12)M`
C. Both (A) and (B)
D. None of these

Answer 1

`{:(,C_(2)O_(4)^(2+)+H_(2)OhArr,HC_(2)O_(4)^(-),+,OH^(-),,K_(h_(1))=(K_(w))/(K_(a_(1)))=(10^(-12))/(5.6)),(t=0,0.005(1-h),0.005h,,0.005h,),(,,~~0.005,,,):}`
`((0.005h)(0.005h))/((0.005))=(10^(-9))/(5.4):.h=1.92xx10^(-4)`
`[OH^(-)]=0.005h=9.6xx10^(-7)M.`
`{:(,HC_(2)O_(4)^(-)+H_(2)OhArr, H_(2)C_(2)O_(4),+,OH^(-),,K_(h_(2))=(K_(w))/(K_(a_(1)))=(10^(-12))/(5.6)),(t=eq,~~9.6xx10^(-7),,,~~9.6xx10^(-7),):}`
`[H_(2)C_(2)O_(4)]=K_(h_(2))=(5)/(28)xx10^(-12)M`