Solubility Curves

Essay by elusive_butterflyHigh School, 11th grade December 2007

download word file, 5 pages 0.0

Purpose: To determine the solubility of potassium nitrate in water at different temperatures to be able to construct a solubility curve for potassium nitrate.

Procedure:1.Labelled 5 test tubes A, B, C, D and E2.Filled each test tube with 5 ml of distilled water.

3.Placed 7.5 g of potassium nitrate in test tube A4.Placed 6.0 g of potassium nitrate in test tube B5.Placed 4.5 g of potassium nitrate in test tube C6.Placed 3.0 g of potassium nitrate in test tube D7.Placed 1.5 f of potassium nitrate in test tube E8.Placed all five test tubes in a 600 ml beaker that was half filled with water.

9.Heated the beaker over a Bunsen burner flame until all of the potassium nitrate dissolved.

10.Turned off Bunsen burner (when all solids dissolved).

11.Removed test tubes from beaker.

12. Placed thermometer, in the solution, in each test tube.

13.Waited for crystals to appear and recorded the temperature at which they did on a data table.

14.repeated steps 12 and 13 for each test tubeObservations:Test TubeTemperature for Re-crystallization (°C)A71B63C56D45E26-when the potassium nitrate was added to the water, before boiling, it sunk to the bottom-the potassium nitrate dissolved in the water at a very high temperature-some white residue was splattered onto the side of the test tube-after dissolving, the KNO3 and water created a clear solution-A white solid was formed in each test tube as the temperatures decreased-The KNO3 in each test tube re-crystallized at a different time-The KNO3 in test tube A was the first to re-crystallize and then B, C, D and E was the last to re-crystallize.

Calculations:1. Using the mass of potassium nitrate dissolved in 5 ml of water; calculate the solubility of potassium nitrate in grams per 100 g of water...