3.
Pragya tested the solubility of
different temperatures and collected the data as given below
(results are given in the following table, as grams of substance
dissolved in 100 grams of water to form a saturated solution)
Substance Dissolved Temperature in K
293
333
Solubility
313
353
283
37
35
54
32 62 106
21
167
Potassium nitrate
36 36 36 37
Sodium chloride
35
Potassium chloride
40 46
Ammonium chloride 24 37 41 55
66
(a) What mass of potassium nitrate would be needed to
produce a saturated solution of potassium nitrate in
50 grams of water at 313 K?
(b) Pragya makes a saturated solution of potassium chloride
in water at 353 K and leaves the solution to cool at room
temperature. What would she observe as the solution
cools? Explain.
(c) Find the solubility of each salt at 293 K. Which salt has
the highest solubility at this temperature?
d) What is the effect of change of temperature on the
solubility of a salt?
Answers
Answer:
(a) At 313 K 62 g of potassium nitrate dissolved in 100 g of water. So to produce a saturated solution of potassium nitrate in 50 g of water we need
100
62
×50=31 g of potassium nitrate.
(b)Some soluble potassium chloride will separate out in the form of crystal at room temperature because the solubility of potassium chloride will decrease.
(c)
(i) Solubility of Potassium nitrate at 293 K is 32 g.
(ii) Solubility of sodium chloride at 293 K is 36 g.
(iii) Solubility of Potassium chloride at 293 K is 35 g.
(iv) Solubility of Ammonium chloride at 293 K is 37 g.
The solubility of Ammonium chloride is highest at this temperature.
(d)The solubility of salt increases with the increase in it is right answer