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
substance dissolved in 100 grams of water to form a saturated solution).
(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 coo! at room temperature. What would she observe us 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. Thus, 31 g potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 g 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. ... (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.The solubility of Sodium chloride at 293 K is = 36 g. The solubility of Potassium chloride at 293 K is = 35 g. The solubility of Ammonium chloride at 293 K is = 37 g.
D.If we heat the solvent, the average kinetic energies of its molecules increases. Hence, the solvent is able to dislodge more particles from the surface of the solute. Thus, increasing the temperature increases the solubilities of substances. For example, sugar and salt are more soluble in water at higher temperatures.
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 temperature.
Explanation:
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