Science Experiment for B2 to work with the Parents/ Whanau

Science Fair    -What melts ice faster?

1. Get the salt, sugar, sand, and measuring teaspoon ready to use nearby.
1. Once you have set up the ice cubes in their bowls, you will want to quickly add the substances to the ice cubes so that they do not melt before adding the substances.
2. Into each of the four bowls, quickly place three ice cubes. Arrange the ice cubes so that only the corners are touching, forming a triangular shape, as shown in Figure 2, below.
1. Tip: If you are using ice cubes from a tray, it helps to let the tray sit at room temperature a little (for about five minutes) so that the ice cubes more easily come out of the tray and do not break into pieces.

Figure 2. Arrange three ice cubes in each bowl so that just the corners of the ice cubes touch each other.

3. Carefully sprinkle ½ teaspoon (tsp.) of salt over the ice cubes in one bowl, as shown in Figure 3, below. Then sprinkle ½ tsp. of sugar over the ice cubes in another bowl, and ½ tsp. of sand over the ice cubes in the third bowl. Do not sprinkle anything over the ice cubes in the fourth bowl — it will be your control.

Figure 3. Sprinkle salt, sugar, sand, or nothing over the ice cubes in each bowl.

4. Move each bowl to an empty shelf in the refrigerator. If any of the ice cubes no longer form a triangular shape in their bowl, gently nudge the ice cubes to make a triangle again.You are doing this experiment in the refrigerator because it is easier to see the effects of colligative properties at colder temperatures. To think about why this is, imagine melting an ice cube on a hot, paved road compared to melting it in the refrigerator. The hot temperature of the road will make all of the ice cubes melt very quickly, which makes it harder to see the relatively minor effects of colligative properties on how fast the ice cubes melt.
5. Note the starting time in your lab notebook. Tell other people who may use the refrigerator that you are doing a science project and to not leave the refrigerator door open long as this could change the temperature of the refrigerator.
6. Check on the ice cubes every hour. When the ice cubes in one of the bowls have become at least half melted, take out all four bowls from the refrigerator and move on to step 7. (Be sure to take the bowls out before the ice cubes in two or more bowls have completely melted.)

Substance	Amount Melted (mL)	Amount Remaining (mL)	Total Amount (mL)	Percentage Melted
Salt
Sugar
Sand
Nothing

1. Depending on how cold your refrigerator is, it may take about four hours for the ice cubes to become at least half melted.
2. While you are waiting, make a data table like Table 1 in your lab notebook.

Table 1. Make a data table like this one in your lab notebook to record your results in. Note that the liquid measurements should be recorded in milliliters (mL).

7. Carefully pour the liquid water from one of the bowls into a cup with a spout, such as a large measuring cup. Make sure the ice cubes stay in the bowl, but get as much liquid into the cup as possible. Then carefully pour the liquid from the cup into the graduated cylinder. Record how much liquid was in the bowl (the amount of ice melted) in the data table in your lab notebook. After recording your results, clean out and dry the cup and graduated cylinder.
1. Alternatively, you could use a funnel instead of a cup with a spout and funnel the liquid directly into the graduated cylinder from the bowl.
8. Repeat step 7 with the three other bowls.
1. When pouring the liquid from the bowl with the sand, try to leave as much sand in the bowl as possible.
9. Now let the ice cubes completely melt in their bowls (you can leave them at room temperature). Once all of the ice cubes are melted, repeat steps 7–8 (but this time you will not need to worry about keeping the ice cubes in the bowls). Record the amount of liquid remaining in each bowl in your data table.
10. Calculate the total amount of water (originally in ice cube form) that was in each bowl. To do this, add the "amount melted" to the "amount remaining" for each bowl. Record the total amount for each bowl in your data table.
1. For example, if the amount melted was 65 mL and the amount remaining was 25 mL, the total amount would be 90 mL.
11. Calculate the percentage of ice that was melted (when you first took the bowls out of the refrigerator) for each bowl. Do this by dividing the amount melted by the total amount.
1. For example, if 65 mL was melted, and the total amount was 90 mL, dividing 65 mL by 90 mL would give you 0.72, which is the same as 72%. This means that 72% of the ice melted.
12. Clean out and dry the bowls. Then repeat steps 1–11 at least two more times so that you have done at least three trials total.
13. Did any of the substances you tested consistently speed up the melting of the ice (compared to the melting rate of plain ice cubes with nothing added)? If so, can you explain your results?
14. Now you are ready to create your science fair display board! If you need help making your display board, a downloadable display board template for this project is available for purchase below. The template provides step-by-step guidance for creating all the usual sections of a display board: title, abstract, background information, question, hypothesis, variables, results, conclusions, and acknowledgements.

Variations

• Does the melting rate depend on the amount of solute added? Design an experiment to find out.
• Investigate the effect of temperature on how colligative properties melt the ice cubes. To do this, try your experiment at different temperatures, such as room temperature or outside on a hot day. Be sure to monitor the temperature regularly throughout your experiment.
• Do other substances help melt the ice cubes more quickly or slowly? Identify some substances to try and then repeat this experiment.
• For a related, more advanced experiment on freezing point depression, see the Science Buddies project Chemistry of Ice-Cream Making: Lowering the Freezing Point of Water
• Do you think salt would melt ice in your freezer? Why or why not? Try it and find out.