Speeding up the melting
process of ice
By: Geert Jaspers and Joris Voorn
Ignatius Gymnasium
Introduction
In daily life, salt is often used for frozen roads.
This will then cause the ice, upon the road, to
melt. The salt, causes the ice to melt faster
than normal, in other words, the melting point
of the ice is now lower than normal. Given
that, it’s important to know that many salts,
such as NaCl, dissolve very well in water.
Apparently, the melting and freezing point of
water decrease when a salt is dissolved in it.
But, what’s the cause of this to happen? One
of the factors that makes one salt different to
another is the difference in molar mass. We
can easily control and regulate that factor by
just picking another salt, with a different
molar mass each time. That raises the
following question: Does the molar mass of
one salt, that is dissolved in water, has
coherence with the melting and freezing point
of that same water. To inquire this we made
up an accurate study design. Before we
started, we presumed that the salt with a
smaller molar mass causes the water, in which
that very salt is dissolved, to have a lower
melting and freezing point.
Experimental design
To figure out which chemical will speed up the
melting process of ice, we have to take four
(plastic) cups filled with water (60 ml). In three
of them we put the different kinds of salts,
NaCl, NaF and KI, all with the same weight. To
mimic the real situation as good as possible it
is important to use as much as 10% of the
weight of the water, that means we used 5,99
grams of each salt. And after one day left in
the freeze, we could start measuring.
Drawing of experimental design
To measure the speed of the melting process
of the different ice cubes as accurate as
possible, we took four burettes. On top of
those we put funnels with a coffee filter in it,
as you can see in the drawing above.
Uppermost lays the cube of ice. And now we
only have to wait, reading out the burette
every two minutes for 40 minutes long. The
results are placed beneath and put into a
graph. Between the parenthesis is given the
molar mass of each salt.
Evaluation
As usual, there is no inquiry without any
mistakes, ours included. But from your
mistakes you learn, but we think we didn’t
make huge mistakes. The main reason for the
mistakes was the lack of really enough time.
Most mistakes are made In the measuring
process, which is inevitable. Beside that we
have measured on two different days, the
consequence of that could be that the
Photo of the experimental design
Results and Conclusion
As you can see in the graph, the water with
NaF dissolved (red line) melted a lot faster
than the water with NaCl dissolved (green
line). That is completely what we expected,
because the molar mass of NaF is smaller than
the molar mass of NaCl. That means there is
more mole of NaF than there is of NaCl in the
same mass of salt. So, you need a lot less NaF
than NaCl to melt the same quantity of ice. On
the contrary, the results we measured with KI
dissolved in water, are quite unexpected.
Reading the results, the ice with KI melted
faster than any other, but that is not what we
expected. We expected that the melting
process of the ice would slow down, instead of
speed up.
That strange result could have many reasons.
One of the reason could be that only that salt
has one more variable comparing to the
others, and that is potassium instead of
sodium. It could be that potassium has more
difficulties to dissolve in water than sodium
does, in any case the dissolving process could
be different than the dissolving process of
sodium.
Maybe that is a good starting point for a new
inquiry. Further questions might also be: are
salts with a smaller molecule mass more costefficient. Or are there other advantages or
disadvantages such as: does it less affect the
environment or does it corrode bikes and cars
far far mor than normal salt? Beside the molar
Time No salt
NaF
NaCl
KI
(min)
(0)
(41,99) (58,44) (166,0)
(ml)
(ml)
(ml)
(ml)
0
0
0
0
0
2
0,01
0,08
0,03
0,18
4
0,01
0,1
0,03
0,2
6
0,01
0,13
0,03
0,21
8
0,01
0,14
0,41
0,62
10
0,01
0,56
0,74
1,01
12
0,01
0,95
1,21
1,32
14
0,01
1,61
1,62
1,88
16
0,01
1,9
2,21
2,19
18
0,01
2,46
2,5
2,52
20
0,33
2,98
2,85
3,26
22
0,88
3,85
3,2
3,77
24
1,48
4,37
3,53
4,4
26
2,03
5,09
3,82
5,02
28
2,63
5,81
3,98
5,58
30
3,24
6,35
4,32
6,63
32
3,64
7,24
4,51
7,6
34
4,3
8,05
4,78
9,18
36
4,7
8,66
5,02
9,79
38
5,33
9,47
5,42
10,73
40
5,96
10,18
5,85
11,88
temperature in the room was different.
Table of results
Volu
14
me
(ml)
12
No salt(0)
10
NaF (41,99)
8
NaCl (58,44)
6
KI (166,0)
4
2
0
-2
0
Time
(min)
Graph
10
20
30
40