How many gram of `CaC_(2)O_(4)` will dissolve in distilled water to make one litre of saturated solution ? `(K_(sp) =2.5xx10^(-9)` and its molecular mass is 128 )

Options

A. 0.0064 g
B. 0.0128 g
C. 0.0032 g
D. 0.0640 g

Answer

A

Explanation

`CaC_(2)O_(4) hArr Ca^(2+)+C_(2)O_(4)^(2-)`
`K_(sp)=[Ca^(+2)][C_(2)O_(4)^(-2)]`
`K_(sp)=s^(2)`
`s=sqrt(K_(sp))=sqrt(2.5 xx 10^(-9))`
`=5 xx 10^(-5) mol L^(-1)`
Solubility of `g L^(-1) =5 xx 10^(-5) xx ` mol. wt.
`=5 xx 10^(-5) xx 128 =0.00640 g L^(-1)`