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activity: Water Purity
Test
The boiling point of pure water is 100 degrees celsius.
If water contains any impurities this will alter its boiling point.
What
you will need:
- 5 samples of water
- tap water, distilled water and 3 other sources (this could be
tap water from a different area, pond water, river water, sea
water)
- accurate thermometer
- several clean, dry
boiling tubes
- clamp stand and boss
- bunsen burner
- test tube rack, or
large beaker to hold the boiling tubes in
- safety glasses
Click here for
more information on collecting water samples.
What
you will do:
- Put some safety glasses
on.
- Pour 2 cm3
of your water sample into a boiling tube.
- Clamp the boiling
tube at a slight angle, so you can heat the bottom of the tube.
Make sure it is not pointing at anyone's face.
- Put the thermometer
into the tube and carefully clamp it, so it doesn't touch the
base or side of the boiling tube.
- Heat the liquid water
until it boils and record the temperature it boils at.
What
do you observe?
You can record your results in a table like this:
| Water
sample |
Boiling
point in degrees celsius |
| tap
water |
|
| distilled
water |
|
| sea
water |
|
| pond
water |
|
| river
water |
|
Questions:
- Which of your water
samples was the purest? Explain your answer.
- How could you have
improved your experiment to make it a fairer test?
- Here are three sources
of water pollution: a) homes, b) farms, c) industries. For each
one of these, list two pollutants that it might produce.
Click
here to
check your answers.
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