Aim: To find out the difference of the boiling point and melting point when adding impurity (salt) to water.
Diagram:
Method: 1.Set up the apparatus as shown in the diagram
2. Get a known amount of ice in the beaker (half full), and a known amount of salt in another beaker
3. Measure the temperature (melting point) of the ice without adding any impurity (salt).
4. Measure the temperature (melting point) of the ice after adding the salt into the beaker.
5. Heat up the beaker with both ice and salt inside
6. Wait until the substance in the beaker boils
7. Measure the temperature (boiling point) of the substance—ice with salt added in when it boils.
Result:
| Melting point/℃ | Boiling point /℃ | Before adding impurity (salt) | 2 | | After adding impurity (salt) | -10 | 107 | Conclusion: As shown from the result table, the temperature of the ice without any impurity is at 2 ℃. Ice is the solid state of water. For ice, the melting point is O℃ that means the ice already started to melt at 2℃. However, after adding the impurity (salt) to the ice, the temperature suddenly decreased to -10℃. This suggests that by adding salt to ice, the temperature drops and the ice melts slower. By adding the salt to ice, the melting rate slows down and the freezing rate increases. Usually, water boils at 100℃, but the added salt makes the substance to boil slower when it’s heated up. Therefore, the result shows that the boiling point was