Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of a substance dissolved in 100 grams of water to form a saturated solution).

Substance dissolved Temperature in K
283 293 313 333 353
  Solubility
Potassium nitrate 21 32 62 106 167
Sodium chloride 36 36 36 37 37
Potassium chloride 35 35 40 46 54
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 313K?

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?

Asked by Vishal kumar | 2 years ago |  301

1 Answer

Solution :-

(a) Given:

Mass of potassium nitrate required to produce a saturated solution in 100 g of water at 313 K = 62g

To find:

Mass of potassium nitrate required to produce a saturated solution in 50 g of water =? 

Required amount = 62 x 50/100 = 31 

Hence 31 g of potassium nitrate is required.

(b) The solubility of potassium chloride in water is decreased when a saturated solution of potassium chloride loses heat at 353 K. Consequently, Pragya would observe crystals of potassium chloride which would have surpassed it solubility at low temperatures.

(c) Listed below is the solubility of each salt at 293 K: 

  • Solubility of Potassium nitrate —> 32/100
  • Solubility of Sodium chloride —> 36/100 
  • Solubility of Potassium chloride —> 35/100   
  • Solubility of Ammonium chloride —> 37/100       

It is observed that the ammonium chloride salt has the highest amount of solubility when compared to any other salt at 293 K.

(d) Effect of change of temperature on the solubility of salts:

The table clearly depicts that the solubility of the salt is dependent upon the temperature and increases with an increase in temperature. With this we can infer that when a salt arrives at it saturation point at a specific temperature, there is a propensity to dissolve more salt through an increase in the temperature of the solution.

Answered by Vishal kumar | 2 years ago

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