Activity

# Can the Boiling Point of Water be Changed?

## Perkins School for the Blind student shares his science fair experiment testing what will happen to boiling water after adding salt.

Perkins School for the Blind Secondary School student Cullen Gallagher shares his science fair experiment testing the hypothesis: “I think the boiling point [of water] will stay the same after adding salt.”

### Scientific Question:

Can the boiling point of water be changed?

### Hypothesis:

I think the boiling point will stay the same after adding salt.

I will boil water and add a substance like salt to see if the boiling point increases.  The lab quest would be used to take temperature.

### Materials

• Hot plate
• Lab quest
• Glass beaker
• Safety goggles
• Lab coat
• Ring stand
• Water
• Salt
• Measuring spoons

### Procedure

1. Assemble ring stand.
2. Place glass beaker in ring stand.  Position beaker over hot plate.
3. Pour 250 mL of water into beaker.
4. Position lab quest probe in water.
5. Turn on lab quest and record water temperature .
6. Turn on hot plate.  Bring water to a boil.
7. Record temp at boiling point.
8. Add 1/2 tsp. salt. Record temp.
9. Repeat step 8 five times.

### Observations:

Beginning water temp. equals 19.2 degrees C.

• Boiling point equals 99.5 degrees C
• 1/2 tsp. salt equals 100.1 degrees C
• 1 tsp. salt equals 100.2 degrees C
• 1 1/2 tsp. salt equals 100.6 degrees C
• 2 tsp. salt equals 100.7 degrees C
• 2 1/2 tsp. salt equals 101.1 degrees C
• 3 tsp. salt equals 101.6 degrees C

### Conclusion:

When I did my experiment, I learned that salt increases the boiling point of water.  Not only does salt raise the boiling point, but it also lowers the freezing point.  When the water finished boiling without salt, the temperature was 99.5 degrees C.  When I added 3 tsp. of salt, the temperature increased to 101.6 degrees C.  My Internet search confirmed this.  If you would like to see the rest of my observations, please see the bar graph.  The molecules moved faster when the temperature was raised.  They also collided more frequently.  I learned a lot by doing this experiment.

Listen to the Radio Interview with Cullen Here