Question

Rama tested the solubility of four substances at different temperatures and found in grams of each substance dissolved in 100 g of water to form a saturated solution

Now answer the following questions :

(a) Which substance is the least soluble at 293 K?

(b) Which substance shows the maximum change in its solubility when the temperature is raised from 293 K to 313 K?

(c) Find the amount of ammonium chloride that will separate out when 55 g of its solution at 333 K is cooled to 293 K?

(d) What is the effect of temperature on the solubility of a salt?

(e) What mass of sodium chloride would be needed to make a saturated solution in 10 g of water at 293 K?

Answer 1

Solubility

The maximum amount of solute that can be dissolved in the given amount of solvent at a specific temperature.

(a) By analyzing the table, potassium nitrate is the least soluble compound at 293 k i.e..,32 g.

(b) To find out the maximum change of solubility when the temperature is raised from 293 K to 313 K, we can find out the change of solubility for each substance.

Ammonium chloride

Solubility at 313 K = 41 g

Solubility at 293 K = 37 g

Change of solubility = Solubility at 313 K - Solubility at 293 K = 41-37 = 4 g

Potassium chloride

Solubility at 313 K = 40 g

Solubility at 293 K = 35 g

Change of solubility = Solubility at 313 K - Solubility at 293 K = 40-35 =5 g

Sodium chloride

Solubility at 313 K = 36 g

Solubility at 293 K = 36 g

Change of solubility = Solubility at 313 K - Solubility at 293 K = 36-36 = 0

Potassium nitrate

Solubility at 313 K = 62 g

Solubility at 293 K = 32 g

Change of solubility = Solubility at 313 K - Solubility at 293 K = 62-32 = 30 g

By analyzing the change, potassium nitrate shows the maximum change in solubility

(c) From the data given here, the solubility of ammonium chloride at 333 K is 55, and solubility at 293 K is 37.

Therefore, the amount of compound that separate out on cooling from 333 K to 293 K is,

Solubility at 333 K - Solubility at 293 K = 55-37 = 18 g.

(d) When we increase the temperature, most of the solids readily dissolve on the solvent.

So, comparing the solubility of salts given in the table, solubility increases with increasing temperature.

The solvent molecules get the energy to break apart the solute molecules when the temperature increases. This causes an increase in the solubility of the salt.

(e) At 293 K, the solubility is given as 36 for sodium chloride.

Solubility gives the amount of solute to make the saturated solution at that temperature. Therefore, 36 g of sodium chloride is required to make the saturated solution in 100 g of water at 293 K.