Question

The precipitate of caF2( ksp=1.7×10*10)is obtained when equal volumes of the following are mixed?

Answer 1

Answer:

The precipitate of CaF

2

(K

sp

=1.7×10

−10

) is not obtained when equal volumes of 10

−4

MCa

2+

+10

−4

MF

−

are mixed. This is because ionic product of calcium fluoride will not exceed solubility product.

Q=[Ca

2+

][F

−

]

2

Q=0.5×10

−4

×(0.5×10

−4

)

2

Q=1.3×10

−13

K

sp

=1.7×10

−10

1.3×10

−13

<1.7×10

−10

Q<K

The precipitate of CaF

2

(K

sp

=1.7×10

−10

) is obtained when equal volumes of 10

−2

MCa

2+

+10

−3

MF

−

are mixed. This is because ionic product of calcium fluoride will exceed solubility product.

Q=[Ca

2+

][F

−

]

2

Q=0.5×10

−2

×(0.5×10

−3

)

2

Q=1.3×10

−9

K

sp

=1.7×10

−10

1.3×10

−9

>1.7×10

−10