Question

500 mL of H20 are saturated with K2SO4 at 70 degrees C. What mass of K2SO4 will crystallize as the solution cools to 10 degrees C? It has a Solubility of Salt Chart. Y- axis is per 100 g H20. X-axis is temperature.

Answer 1

I am assuming solubility of K₂SO₄ at 70^oC = 20 g / 100 g H₂O

solubility of K₂SO₄ at 10^oC = 10 g / 100 g H₂O

density of water = 1.00 g/mL

mass of water = volume * density = (500 mL) * (1.00 g/mL) = 500 g

When temperature changes from 70^oC to 10^oC ,

mass of K₂SO₄ crystallizes out of solution = (20 g / 100 g H₂O) - (10 g / 100 g H₂O)

mass of K₂SO₄ crystallizes out of solution = 10 g / 100 g H₂O

Total mass of K₂SO₄ = (mass of K₂SO₄ crystallizes out of solution) * (mass of water)

Total mass of K₂SO₄ = (10 g / 100 g H₂O) * (500 g H₂O)

Total mass of K₂SO₄ = 50 g