EXPERIMENTAL SCIENCE PROJECTS:
The Effect of Salt on the Boiling Temperature of Water
(Initially prepared by a 4th Grade student)
To quickly jump to a section below click on:
| Initial Observation | Title
| Purpose | Hypothesis
| Materials | Procedure
| Data |
| Experimental Observations
| Calculations| Results
| Conclusions | Questions
|
INITIAL
OBSERVATION
Cooking instructions tell you to add salt to water before boiling
it.
PROJECT
TITLE
The Effect of Salt on the Boiling Temperature of Water
PURPOSE
OF THE PROJECT
To find out how table salt affects the boiling temperature
of water.
HYPOTHESIS
Adding table salt to boiling water will cause the water to
boil at a higher temperature.
MATERIALS
AND EQUIPMENT
- Table Salt
- Distilled Water
- 2 Quart Cooking Pot
- Pint measuring cup
- Teaspoon and tablespoon measuring spoons
- Thermometer
- Stirring spoon
EXPERIMENTAL
PROCEDURE
- Boil one quart of distilled water on a stove.
- Measure the temperature of the boiling water. Record the
highest temperature reading. This is the control
to compare with.
- Measure out table salt using a kitchen measuring spoon. Level
the spoonful.
- Add the measured salt to the boiling water and stir.
- Measure the temperature of the boiling water with the salt
in it. Record the highest temperature reading.
- Repeat for other amounts of salt.
DATA
Data Obtained: 2/25/95, Mankato, MN
Amount of boiling water |
2 Cups |
Temperature of boiling water (Control) |
212.9°F |
Amount of table salt added to boiling water: Run #1 |
1 Tbl. |
Temperature of boiling water after adding salt: Run #1 |
215.6°F |
Additional amount of table salt added to boiling water: Run #2 |
1 Tbl. |
Temperature of boiling water after adding salt: Run #2 |
218.3°F |
|
|
EXPERIMENTAL
OBSERVATIONS
When the salt was added to boiling water it bubbled up more,
and then stopped boiling. Shortly afterwards, it boiled again.
If the thermometer extends beyond the outside of the pot it
reads a higher temperature. Heat from the stove burner makes the
thermometer read higher. Keep the thermometer over the pot when
making temperature measurements.
CALCULATIONS
- Total amount of table salt added for Run #1: 0 + 1
= 1 Tbl.
- Total amount of table salt added for Run #2: 1 + 1
= 2 Tbl.
RESULTS
Temperature of boiling water (Control) |
212.9°F |
Amount of table salt added to boiling water: Run #1 |
1 Tbl. |
Temperature of boiling water after adding salt: Run #1 |
215.6°F |
Total amount of table salt added to boiling water: Run #2 |
2 Tbl. |
Temperature of boiling water after adding salt: Run #2 |
218.3°F |
|
|
Amount of Table Salt Added Versus
Water Boiling Temperature
CONCLUSIONS
- Is the hypothesis correct?
Yes. Adding table salt to water causes the water to boil at a
higher temperature.
- Problems with doing the experiments.
The temperature readings were hard to make. Gloves had to be
worn to keep my hands from getting too hot. Had to be careful
that the stove heat was not hitting the thermometer.
- Other things learned.
Be careful when adding salt to boiling water. It makes the water
boil vigorously for a second or two.
RELATED
QUESTIONS
- Why do you think cooking instructions tell you to add salt
when boiling water?
When the water is hotter, you can cook food faster. Salt also
makes the food taste better.