Answer to Question #80446 in General Chemistry for Tenderin H

Question

if 300 g of KNO3 are dissolved in 200 g of water at 80 degrees celsius, then how many grams of KNO3 would precipitate out of solution if the temperature were lowered to 30 degrees celsius?
Thanks!

Answer 1

You can determine how many grams of KNO3 can be dissolved in 100 g of water at 30°C by taking a look at its solubility graph.
At 30°C KNO3 has a solubility of approximately 45g/100gH2O.
As temperature decreases, its solubility decreases as well.
At 30°C 90 g KNO3 can be dissolved in 200 g of water.
Then 300 - 90 = 210 g of KNO3 would precipitate out of solution if the temperature were lowered from 80°C to 30°C.