Question

The solubility of CaCl2 in water at 25°C is 81.1 g/100 mL; at 0°C its solubility decreases to 59.5 g/100 mL. Answer the following questions about an aqueous solution of 26.4 g of CaCl2 in a volume of 37.5 mL: a. At 25°C, is this a saturated solution? b. If the solution is cooled to 0°C, do you expect a precipitate to form? c. If the solution is slowly cooled to 0°C and no precipitate forms, then what kind of solution is it?

Answer 1

Given solubility at

1) 25C is 81.1g/100ml

2) 0C is 59.5g/100ml

a)If 26.4 g of CaCl2 is dissolves in 37.5ml, then in 100 ml of this solution, amount of CaCl2 is (26.4/37.5)*100 = 70.4 grams. So this is not a saturated solution as maximum amount which can be dissolved is 81.1g.

b)At 0C, this solution becomes satutaed as it can hold only 59.5g/100ml. So, precipitate will be formed.

c)If it is slowly cooled and no precipitate is formes, it is known as supersaturated solution.