How fast ice melts when exposed to

different substances

By Alwyn Dippenaar

Question: Which substance causes ice

to melt the fastest?

Hypothesis:

If rock salt is put on the ice, then ice will melt fastest because salt lowers the freezing point and rock salt has the biggest surface area of any salt, surface area allows a bigger area of contact.

Materials

• 6 see-through containers

• 6 identically sized cubes of ice

• Measuring spoon – 1Tsp or 5ml

• 5 substances: rock salt, table salt, baking soda, castor sugar, brown sugar

Procedure

1. Lay out 6 identical containers.

2. Place equally sized cubes of ice in each one.

3. Put exactly 1Tsp of each substance on one of the cubes of ice, repeat for 5 of them.

4. Leave one cube of ice as a control.

5. Monitor every 2 minutes, photographing every 10 minutes until ice melts.

6. Record observations.

Constants

Container, cubes of ice, amount of substance, temperature in room, time between observations.

Independent variable

Substance to put on the ice.

Dependent variable

Speed at which the cube of ice melts.

Data and ObservationsAfter 10 minutes

Observations

The rock salt cube showed the most melting and the control cube the least.

Data and ObservationsAfter 20 minutes

Observations

The rock salt cube showed the most change, but table salt a close second and the control cube the least.

Data and ObservationsAfter 30 minutes

Observations

The rock salt cube still showed the most change and the control cube the least.

Data and ObservationsAfter 40 minutes

Observations

The rock salt cube was still best, the table salt second and brown sugar was close behind. The control cube

is still having the least change.

Data and ObservationsAfter 50 minutes

Observations

The rock salt and table salt cubes have melted at this time but the sugars are close.

Data and ObservationsAfter 60 minutes

Observations

In this slide you can see they are all nearly finished.

Data and ObservationsAt 80 minutes

Time to melt with different substances

47 50

71

60 59

70

0

10

20

30

40

50

60

70

80

90

100

Rock salt Table salt Bakingsoda

Castorsugar

Brownsugar

Control

time (mins)

time(mins)

Conclusion

In conclusion the rock salt did best as I suspected and as I said before I think it is because any salt will do but rock salt is biggest so it works best. You may have noticed in the graph that baking soda took longer than the control. I think this is because I noticed when the ice was small enough the foaming baking soda was covering the ice and so it insulated it from heat.