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2. Method
2.1 Equipment list:
- Temperature probes x6
- Table salt (500g) x2
- metal cups x 9
- Refrigerator (-22 degrees Celsius)
- Electronic balance
- 2 pairs of thongs
- Data logger x2
- foam box
2.2 Diagrams
Figure 1: Experimental setup (using refrigerator)
2.3 Procedures: Detail all procedures and experimental designs to be used for data collection
Prepare 6 metal cups.
Ensure that the tap water is at room temperature.
Pour 200ml of tap water into each metal cup (use a beaker to measure 200ml of water).
Add 0g, 10g,50g, 54g, 58g, 60g of fine salt into each metal container respectively.
Stir the mixture well to ensure that the fine salt is dissolved in the tap water.
Place 1 temperature sensor into each cup of water.
Place each metal container into the freezer.
Ensure that the wire is outside the freezer and in a place where it is easily found.
Check the setups in the freezer after the first 10 minutes to ensure that the temperature sensor did not go out of the water.
Before taking the frozen out, set the data logger to at least 3h and record data at an interval of 3 per minute.
Ensure that solution has frozen. Take the metal cups out of the freezer 3 at a time. (Use of thongs and thick gloves are recommended but not necessary)
Immediately connect the temperature sensors to the data logger.
Once connected start the data logging and leave it to melt for at least 3h.
Once the time is up, save the data to a USB flash drive.
Repeat steps 8 to 14 for the rest of the beakers.
Wash the cups before using them again, to ensure that no salt is left from the previous experiment.
Repeat the experiment at least 1 time for each solution.
2.4 Data analysis
18. The graph below shows the melting point against the concentration of salt.
The melting point is when the temperature remains constant for a longer duration.
19. Plot a table of melting point against the different concentrations of salt.
20. Plot a graph of Melting point against the salt concentration of water. The graph below shows the supposed results of the experiment.
Figure 3: Expected melting point against salinity of water (in g/kg)
21. From the graph above we can find out if the freezing point of water will change with different salt concentrations.
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