Question

Khoisan salts is the number 1 producer of salts in SA for both local and international markets. 500 kg of KCl is dissolved in sufficient water to make a saturated solution at 370 K. At 370 Kthe solubility of KCl is 42 mass %. The solution is cooled to 320 K and the solubility is 31,5 mass % It is assumed that no water is evaporated. 2.1. Determine the amount of water is added to the 500 kg of KCl to produce the required saturated solution at 370 K. (3) 2.2. Determine the mass of KCl crystals formed after the cooling process to a temperature of 320 K. (Use the formula method)

Answer 1

1. 690 kg of water.
2. 125 kg of KCl crystals are formed after cooling process

Step-by-step explanation:

1) A saturated solution is a chemical solution containing the maximum concentration of a solute dissolved in the solvent. The solubility of KCl at 370K is 42%mass -42kg of KCl in 100kg of water+KCl , thus, the amount of water added to 500kg of KCl is:

500 kg of KCl ×
`(100 kg Water+KCl)/(42kgKCl)` = 1190 kg of water +KCl

1190 kg of water +KCl - 500 kg of KCl = 690 kg of water

2) The maximum amount that this solution could solubilize of KCl at 320K is:

1190 kg of water + KCl ×
`(31,5 kgKCl)/(100kgWater+KCl)` = 375 kg

Thus, the mass of KCl crystals formed are:

500 kg of KCl - 375 Kg of KCl = 125 kg of KCl

I hope it helps!