EXPERIMENT (5) Effect of Temperature on Solubility of a Salt

Aim of The Experiment: Study the effect of changing temperature on the amount of solute that will dissolve in a given amount of water For Example: In this experiment, you will completely dissolve different quantities of potassium nitrate, KNO3, in the same volume of water at a high temperature.

Theory: water solubility: is an important physical property in chemistry, expressed as the mass of solute that dissolve in 100g of H2O at a certain temperature.

Procedure: Add 5 ml of distilled water to each test tube. Label four test tubes 1-4. Add 5 ml of distilled water to each test tube. Fill a 250 ml beaker with tap water and heat the water bath to about 90 C. Lower the test tube into the water bath and stir the mixture until the KNO3 is completely dissolved ( HINT: test tubes 3 & 4 need to be heated to a higher temperature than test tubes 1& 2) As each solution cools you will monitor temperature when solid crystals start to form ( T ). Repeat steps 4 & 5 for each of the test tube. Test tube number Amount of KNO3 used per 5ml H2O Amount of KNO3 used per 100g H2O 1 2 40 4 80 3 6 120 8 160

Procedure: Where X gm in test tube 1 = 2 gm X gm in test tube 2 = 4 gm

ᴼC Results: At this temperature for each test tubes , The solution is saturated and contains the maximum amount of solute at that temperature. Trial Solubility (x gm KNO3/ 100 gm H2O) Temperature ᴼC 1 40 2 80 3 120 4 160

Graph: A graph of the temperature-solubility data consists of a solubility value (g of solute per 100g of H2O) and a corresponding temperature known as a solubility curve. Super Saturated Saturated Solubility Un Saturated Temperature ᴼC