Calculate the concentration of f- in a solution saturated with mgf2 an

1.	Calculate the concentration of f- in a solution saturated with mgf2 and srf2. Given ksp of mgf2 is 9.510-9 and ksp of srf2 is 410-9
Answer» $[F^-]=1.59\times 10^{-4}mol./L$ Answer: TOTAL CONCENTRATION of FLUORINE IONS Explanation: 1) $MgF_2\rightleftharpoons Mg^{2+}+2F^-$ S 2S $K_{sp}$ of $MgF_2$ = $9.5\times 10^{-9}=[S][2S]^2=4S^2$ $S=4.87\times 10^{-5} mol/L$ Concentration of fluorine ions in saturated SOLUTION of $MgF_2$ $[F^-]_{MgF_2}=2S=2\times 4.87\times 10^{-5} mol/L=9.74\times 10^{-5}mol/L$ ...(1) 2) $SrF_2\rightleftharpoons Sr^{2+}+2F^-$ S' 2S' $K_{sp}$ of $SrF_2$ = $4\times 10^{-9}=[S'][2S']^2=4S'^2$ $S'=3.1\times 10^{-5}mol/L$ Concentration of fluorine ions in saturated solution of $SrF_2$ $[F^-]_{SrF_2}=2S=2\times 3.1\times 10^{-5} mol/L=6.2\times 10^{-5}mol/L$ ...(2) $[F^-]$ Total Concentration of fluorine ions $=[F^-]_{MgF_2}+[F^-]_{SrF_2}=9.74\times 10^{-5}mol/L+6.2\times 10^{-5}mol/L=15.94\times 10^{-5}mol/L=1.59\times 10^{-4}mol./L$

Calculate the concentration of f- in a solution saturated with mgf2 and srf2. Given ksp of mgf2 is 9.510-9 and ksp of srf2 is 410-9

Answer»

$[F^-]=1.59\times 10^{-4}mol./L$ Answer: TOTAL CONCENTRATION of FLUORINE IONS

Explanation:

1) $MgF_2\rightleftharpoons Mg^{2+}+2F^-$

S 2S

$K_{sp}$ of $MgF_2$ = $9.5\times 10^{-9}=[S][2S]^2=4S^2$

$S=4.87\times 10^{-5} mol/L$

Concentration of fluorine ions in saturated SOLUTION of $MgF_2$

$[F^-]_{MgF_2}=2S=2\times 4.87\times 10^{-5} mol/L=9.74\times 10^{-5}mol/L$ ...(1)

2) $SrF_2\rightleftharpoons Sr^{2+}+2F^-$

S' 2S'

$K_{sp}$ of $SrF_2$ = $4\times 10^{-9}=[S'][2S']^2=4S'^2$

$S'=3.1\times 10^{-5}mol/L$

Concentration of fluorine ions in saturated solution of $SrF_2$

$[F^-]_{SrF_2}=2S=2\times 3.1\times 10^{-5} mol/L=6.2\times 10^{-5}mol/L$ ...(2)

$[F^-]$ Total Concentration of fluorine ions

$=[F^-]_{MgF_2}+[F^-]_{SrF_2}=9.74\times 10^{-5}mol/L+6.2\times 10^{-5}mol/L=15.94\times 10^{-5}mol/L=1.59\times 10^{-4}mol./L$