Solubility Curves

How much solute can a solvent (H2O) hold? Depends on amount of solvent & temperature (Pressure for gases) Increasing the temperature increases the solubility of a solid solute Increasing the temperature decreases the solubility of a gaseous solute Increasing the pressure increases the solubility of a gaseous solute

Solubility Curves shows how much solute will dissolve in 100g of water over a range of temperatures

sol’n contains the maximum amount of dissolved solute too much solute was added the sol’n is saturated and there is extra (on bottom if solid) not enough solute was added and the sol’n is UNsaturated

too much solute not enough solute just right

Solution Equilibrium At the point of saturation, solution equilibrium exists Where the precipitate and water meet, the rate of dissolving equals the rate of crystalization

KCl What mass of KCl will dissolve in 100g of water at 60oC?

45g KCl What mass of KCl will dissolve in 100g of water at 60oC? The graph is written for 100g of water. If you have 200g of water then you can double the amount of solute dissolved = 90g

80g of KCl is added to 100g of water at 60oC how much solute will precipitate out of sol’n?

80g of KCl is added to 100g of water at 60oC how much solute will precipitate out of sol’n? The data point is above the KCl line. It is saturated at 45g. If you try to add 80g, then the difference will sink to the bottom. 80g 45g 35 g

20g of KCl is added to 100g of water at 30oC what kind of sol’n is made? How much more solute could be added to make the sol’n saturated?

20g of KCl is added to 100g of water at 30oC what kind of sol’n is made? This data point is below the KCl line and so the solution is UNSATURATED. How much more solute could be added to make the sol’n saturated? A saturated sol’n will hold about 32g so the difference is how much more you can add. 32g-20g = 12g

The End