Question

a. Equal volumes of `0.02M CaC1_(2)` and `0.04M Na_(2)SO_(4)` are mixed. Will a precipitate form? `K_(sp)` of `CaSO_(4) = 2.4 xx 10^(-5)`

Answer 1

`{:(,CaCI_(2)+,Na_(2)SO_(4)rarr,CaSO_(4)+,2NaCI),("Millimole added",0.02V,0.004xxV,0,0):}`
Suppose `VmL` of both are mixed
`:. [Ca^(2+)] = (0.02V)/(2V) [SO_(4)^(2-)] = (0.0004V)/(2V)`
`:. [Ca^(2+)] [SO_(4)^(2-)] = (0.02V) xx (0.0004V)/(2V) = 2 xx 10^(-6)`
Thus, `[Ca^(2+)] [SO_(4)^(2-)]` in solution `lt K_(sp)`
`2 xx 10^(-6) lt 2.4 xx 10^(-5)`
`:. CaSO_(4)` will not precipitate.