Problem Does Hot Water or Cold Water Freeze Faster? Experiment Problem Does Hot Water or Cold Water Freeze Faster? Experiment Done By: Hannah Mitchum

My Hypothesis If I freeze hot water and cold water the cold water will freeze faster than the hot water.

Materials 2 Rubbermaid plastic containers (296ml) metal cooking pan Stove one bottle of Aquafina water Thermometer pot holder ½ cup measuring cup freezer.

Procedure

Procedure #1: Set up materials. (Specifically: Gather all materials in the kitchen, place all materials on the counter and the place the pan on the stove. I will make sure the freezer is cleared so the containers have a clean flat space to sit) #2 Pour ½ cup of water into a pan/ Set pan on stove bring to a boil/Pour into set container for hot water(marked with brown line) /Take temperature with thermometer and record #3 Pour ½ cup of cold water that has been kept in the refrigerator into the set container/Take Temperature with thermometer and record #4 Place containers in the freezer set at -2 degrees (F) #5 Check every 5 minutes to see the progress. (To check and see if they are frozen I will look at and touch the water to determine progress)/Record data. Repeat until both containers of water are frozen solid.

Process of freezing Completely Liquid Half way frozen

Experiment Experiment: The experiment took place on 9/21/2013. Both the hot and cold water came from the same Aquafina bottle. The hot water was brought to a boil on the stove in a pan. Then the temperature was taken of both the cold and hot water. Hot water was 216 degrees (F) at the time it was placed in the freezer Cold water was at 33 degrees (F) at the time it was placed in the freezer Both hot and cold water was placed in identical containers. The hot water was marked with a brown line on the outside. They were placed side by side into the freezer that was -2 degrees (F). Every 5 minutes the containers were checked and results were recorded based on the appearance of the water in the container and based on my touch. The water was placed in the freezer at 11:00am

Data Collected 11:00: Both the hot water and cold water were completely liquid. 11:05: Both the hot water and cold water were completely liquid. 11:10 Both the hot water and cold water were completely liquid. 11:15 The hot water is still liquid but is getting colder. The cold water is getting ice crystals on the sides and a few in the center. 11:20 The hot water is still completely liquid. The cold water is getting more ice crystals all over. 11:25 The hot water is showing no signs of freezing. The cold water’s surface is starting to freeze, though it is extremely thin. 11:30 The hot water is showing no signs if freezing still all liquid. The cold water’s surface is frozen about a centimeter thick. 11:35 The hot water is starting to freeze around the edge of the container. The cold water’s surface is frozen appears to be about 2 centimeters thick and crystals of water can be seen, but the water is liquid under the top frozen layer. 11:40 The hot water is freezing on the edge of the container and ice crystals can be seen. The cold water appears to be getting thicker. I can see it is still liquid under the surface. 11:45 The hot water is starting to freeze on the surface. The cold water is still only frozen on the surface but you can start to see areas where the water is freezing below the surface. 11:50 The hot water is frozen on the surface. The cold water looks like it still has large pockets of liquid . 11:55 The hot water is frozen on the surface and starting to freeze underneath you can tell that because there are pockets of liquid underneath. The cold water has several pockets of liquid underneath the frozen surface. 12:00 The hot water is frozen on the surface and starting to freeze underneath you can tell that because there are pockets of liquid underneath. The cold water has several pockets of liquid underneath the frozen surface. The bottom layer is still all liquid in both containers. 12:05 The hot water now looks like the cold water. They both are almost solid with a few pockets of liquid throughout and the bottom of both containers is still liquid. 12:10 Both are almost solid with a few pockets of liquid throughout and the bottom of both containers is still liquid. 12:15 The hot water now looks more frozen than the cold water it is almost completely solid and the surface is hard enough that my tough doesn’t affect it. The cold water still has areas that are still liquid the bottom layer is still all liquid 12:20 The hot water is almost all frozen except the bottom still has liquid. The cold water is starting to get more solid. The pockets of liquid are getting smaller. 12:25 The hot water is almost all frozen except the bottom still has liquid. The cold water is starting to get more solid. The pockets of liquid are getting smaller. 12:30 The hot water is frozen except a small amount of liquid is still visible from the bottom. The cold water is almost frozen but still has pockets of liquid near the bottom. 12:35 The hot water is frozen except a small amount of liquid is still visible from the bottom. The cold water is almost frozen but still has pockets of liquid near the bottom. 12:40 The hot water is completely frozen. There is no more liquid in the container. The cold water is almost frozen but the bottom still has liquid. 12:45 The cold water is almost frozen. The bottom has very little liquid left. 12:50 The cold water is almost frozen. The bottom has almost no liquid left. 12:55 The cold water is completely frozen.

Conclusion and Analysis After completing the experiment my results showed that hot water freezes faster than cold water. The cold water started to freeze faster than the hot water but the hot water caught up with the cold water, then turned solid faster than the cold water. The hot water was frozen solid at 1 hour and 40 minutes. The cold water was frozen solid at 1 hour and 55 minutes. The hot water froze 15 minutes faster than the cold water. The results proved that my hypothesis was wrong because I guessed that cold water would freeze faster than hot water. The results of the experiment show that even though cold water is closer to freezing temperatures than the hot water at the start of the experiment the hot water reaches 0 degrees (F) and becomes a solid faster.

Conclusion and Analysis The time it took for the water to freeze could have been affected by the fact that I checked on the containers every 5 minutes, the results might be different if I checked the water every 10 minutes. The water might have frozen faster if I checked every 10 minutes because the temperature would have been more constant inside the freezer. People can use this knowledge when they need to freeze water fast. For example if someone was having a party and wanted to freeze water for ice cubes and they didn’t have a lot of time before the party started based on my results using hot water would take them less time.

The End