Investigating Solubility How does the solubility of Potassium Chloride and Potassium Iodide in water, vary with temperature?

Essay by ikhs0324High School, 11th gradeB+, December 2008

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How does the solubility of Potassium Chloride (KCl) and Potassium Iodide (KI) in water vary with temperature?


To observe solubilities of KCl and KI with water at different temperatures

To compare the two solubility curves and discuss what might vary the solubility of different ionic compounds.

The variables

Dependent variable


Independent variable

Amount of solute (KCl, KI)


Amount of the solvent (water), pressure


100g of Potassium Chloride

100g of Potassium Iodide

10ml cylinder

Test tubes x 15


Glass rod

Beakers x 5

Distilled water


Hot plate

Ice - to cool down the water

Thermometer (0°C to 100°C) x 2


In this experiment different amount of solute were combined with 10ml of water (solvent) which originally was at 0°C. The solvent and solute were mixed together and the temperature where the solute is completely dissolved to the solvent is measured.

Weigh different amounts of KCl and KI

KCl - 6g, 7g, 8g, 9g, 10g (approx.)

KI - 12g, 14g, 16g, 20g, 25g (approx.)

Measure 10ml of water and place them into test tubes

Place the test tubes into ice and wait till they cool to 0°C

Start dissolving the substances into cooled distilled water with the smallest amount of substances

Use a glass rod to stir or a stopper to shake

Measure the temperature at where the substances are covmpletely dissolved

Repeat the process for each gram of the substances - use hot plates with water bath on top where appropriate to get higher temperature.

Data collection and processing

Potassium Chloride

When Potassium Chloride is completely dissolved in water, it becomes clear solution without any solid left in the solution.

Trial 1

Amount of KCl

Temperature that KCl is dissolved

5.909 g ±0.1mg

7 °C ±0.1°C

Amount of water = 10cm3±0.1 cm3 x 2...