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Equilibrium

Question
CBSEENCH11006606
Wired Faculty App

The solubility of CaF2 in water at 298K is 1·7×10–3 gram per 100 cm3. Calculate the solubility product of CaF2 at 298K.

Solution
The molecular mass of CaF2
                           equals space 40 plus space 2 space cross times 19 space equals space 78
Solubility of CaF2 = 1.7 x 10-3 g/100 cm3
                          = 1.7 x 10-2 g L-1

                          equals space fraction numerator 1.7 space cross times 10 to the power of negative 2 end exponent over denominator 78 end fraction mol space straight L to the power of negative 1 end exponent equals space 2.18 space cross times space 10 to the power of 4 space mol space straight L to the power of negative 1 end exponent
The solubility equilibrium is
           
 CaF subscript 2 space rightwards harpoon over leftwards harpoon space space space space Ca to the power of 2 plus end exponent space plus space 2 straight F to the power of minus
i.e. 1 mole of CaF2 in the solution gives 1 mole of Ca2+ ions and 2 moles of F- ions. Hence in the solution.
   open square brackets Ca to the power of 2 plus end exponent close square brackets space equals space 2.18 space cross times space 10 to the power of negative 4 end exponent space mol space straight L to the power of negative 1 end exponent open square brackets straight F to the power of minus close square brackets space equals space 2 space cross times space left parenthesis 2.18 space cross times space 10 to the power of negative 4 end exponent right parenthesis space space space space space space space space space equals space 4.36 space cross times space 10 to the power of negative 4 end exponent space mol space straight L to the power of negative 1 end exponent
 Applying the law of solubility product
       straight K subscript sp space equals space open square brackets Ca to the power of 2 plus end exponent close square brackets space space open square brackets straight F to the power of negative 1 end exponent close square brackets squared space space space space space space space equals space left parenthesis 2.18 space cross times space 10 to the power of negative 4 end exponent right parenthesis thin space left parenthesis 4.36 space cross times space 10 to the power of negative 4 end exponent right parenthesis squared space space space space space space space equals 4.14 space cross times space 10 to the power of negative 11 end exponent

Some More Questions From Equilibrium Chapter

Which measurable property becomes constant in water vapour equilibrium?

Give an example from daily life in which there is gas solution equilibrium?

A crystal of common salt of a given mass is kept in its aqueous solution. After 24 hours, its mass remains the same. Is the crystal in equilibrium with the solution?

What is the role of forward and backward reactions at equilibrium of a reversible reaction?

What is a forward reaction?

What condition favours a reversible reaction?

What is a backward reaction?

What type of equilibrium is attained in a reversibe chemical change?

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