The Boiling Point Of Water
With and without salt
My aim in this scientific investigation was to find out how salt in boiling water affects the time
and temperature it takes to boil. Then I would compare the two sets of data I collected from the
two experiments and compare to see how.
“How does salt and other compounds affect the time it takes to get water at its boiling point”
My background information
The boiling point: In liquid, molecules are packed closely together with random movements. As
we heat the water the temperature rises and then there is lots of vibration. As the molecules
vibrate and they go into a molecular motion which looks like moving a lot they slip past each
other which then allow water to become gas.
Water boils at 100 degrees Celsius (at sea level). As you boil water at higher
places above sea level the boiling point is lower and if you boil water at a place
below sea level the boiling point will be higher. This is due to the fact that if
you are lower than sea level the atmosphere pressure is higher so therefore it
takes longer for the water to boil.
These two points are linked because when there is less pressure in the
atmosphere then there is nothing restraining the molecules from vibrating.
I think the salt in the water will pose as an obstacle towards the vibrating molecules, just like the
pressure in the atmosphere. This results in a higher temperature to take water to its boiling point.
I think that it would be difficult to maintain a temperature of 100 degrees Celsius with distilled
water because we are above sea level. With the salt (NaCl) I think it will take a greater
temperature to boil due to the fact it takes more space.
Independent variable: salt because it is simply what we are testing.
Dependent variable: boiling point
Constant variable: The amount of water in each beaker
Stop watch Measuring cylinder (100ml) Beaker 30% Salt (NaCl)
Wire gauge Electronic heater thermometer Tongs Tripod stand
This experiment has various harmful and hot things such as the Bunsen burner and
the water that is going above 100 degrees Celsius. We wore aprons incase the beaker
spilt or fell and we wore glasses as a normal safety procedure. We have to be extra
careful here because we are dealing with fire. In case something happens I would
run immediately and turn the gas off. There is also the fire extinguisher on the door.
We first got our help sheet to give us some
guidelines. My partner was Sandip, Ms. Maya gave us the 30% salt mixed with water already so
all we had to do was take 100ml. We used the tripod with the special sheet to prevent any
equipment we used to be affected by the flame. I lit the Bunsen burner (with a certain degree of
safety) we took readings every 1 minute for both experiments. Sandip and I drew up tables and
graphs so we could present our findings in the best way possible.
Boiling point of water with salt Difference Boiling point of distilled water
Data and observation
1, 5 degrees Temperature
2, 3.4 degrees 2 45.6
1 33.7 3, 8.1 degrees 3 58.1
2 43.2 4 62.9
4, 2.3 degrees
3 50.0 5 74.5
4 60.6 5, 6.7 degrees
5 67.8 6, 1.2 degrees 7 86.4
6 78.8 8 91.0
7, 3.3 degrees
7 83.1 9 95.4
8, 1.5 degrees
8 89.5 10 99.3
9 91.8 9, 3.6 degrees
10 98.2 10, 1.1 degrees
Tempreature of salt water
Tempreature of water without
1 2 3 4 5 6 7 8 9 10 11 12 13
Analysis of Data
I found that our readings were reliable and the graph shows the difference. It took nine minutes
for the water without salt to start boiling vigorously and it took 11minutes and 47 seconds. I have
seen the differences and was astound at how close they were in temperature but boiling wise I
knew that the distilled water would start boiling vigorously a lot sooner than the other group. I
think that from the data I could see the difference in the beginning. The water would take off but
as the distilled water neared its boiling point but it started boiling a lot faster. The difference in
the two were 1 because of the altitude and 2 because the other one had salt which leashed the
vibration and molecular which needs more heat.
My hypothesis was more or less correct; I observed the data and understood the tables and
results. The hypotheses passed the secret for me to understand why the distilled water started
boiling faster at 9 minutes and the salt water took 11 minutes and 45 seconds to start boiling. I
would say that this science investigation was a success even though we didn’t take results two
times. This investigation really showed me how much salt can really affect water at its boiling
point. Therefore I conclude that salt and other compounds affect at which the temperature it takes
to boil water by simply blocking the molecules from turning into gas.