The effect of salt and sugar on the freezing point of water
The materials required for this science fair project:
- 1 packet of sugar
- 1 packet of salt
- 800ml of distilled water
- 8 test tubes
- 8 beakers
- 1 basin
- Tap water
- 1 freezer
- Ice cube trays
- 8 thermometers
- 1 digital weighing scale
- 1 black marker
1. For this science fair project, the independent variable is the amount of salt and sugar added to the solution. The dependent variable is the freezing point of the solution, and will be measured with a thermometer. The constants (control variables) are the temperature of the environment (which will remain at room temperature), the amount of solution in each test tube and the temperature of the ice in the basin.
2. Mix 200g of salt into in 1 liter of water and pour the solution into ice cube trays. Place the trays in a freezer, and leave overnight. The ice will be used to form an ice bath in the basin.
3. On the 2nd day, label the 8 beakers and test tubes as Salt 0.5M, Salt 1.0M, Salt 1.5M, Salt 2.0M, Sugar 0.5M, Sugar 1.0M, Sugar 1.5M and Sugar 2.0M.
4. Prepare 8 varieties of solution in each beaker as described below:
a. Salt 0.5M – Mix 100ml of water with 2.9g of salt
b. Salt 1.0M – Mix 100ml of water with 5.8g of salt
c. Salt 1.5M – Mix 100ml of water with 8.7g of salt
d. Salt 2.0M – Mix 100ml of water with 11.6g of salt
e. Sugar 0.5M – Mix 100ml of water with 17g of salt
f. Sugar 1.0M – Mix 100ml of water with 34g of salt
g. Sugar 1.5M – Mix 100ml of water with 51g of salt
h. Sugar 2.0M – Mix 100ml of water with 68g of salt
5. Fill a basin with the ice cubes prepared earlier, to create an ice bath.
6. Pour the solution in each beaker into its respective test tube to the halfway mark, or about a height of 5 cm. Place a thermometer into each test tube. Then, place the 8 test tubes into the ice bath.
7. Observe when the first ice crystals start to form, and record the temperature in a table, as shown below.