Here are three experimental questions to answer:
1. Does hot water or cold water freeze faster?
They freeze at the same rate.
2. Does hot water or cold water boil faster?
They boil at the same rate.
3. Does salt water freeze faster or slower than regular water?
Slower.
Questions/Items to then include in you blog posting for this activity:
1. Pictures of your experimental materials and setup.
2. Your hypothesis to the questions posed.
I predict that cold water would freeze faster because it is already closer to the temperature that it needs to reach in order to freeze. With that said, I predict that hot water would boil faster because it is closer to the temperature that it needs to reach in order to boil. I also predict that salt water would freeze slower than regular water because there is salt in there that will throw off the freezing process (I also thought of the ocean and that doesn’t freeze! Not sure if that is because of the water amount or the type of water though!).
| | Freezing time | Boiling time |
| Hot water (1 c. water) | 1 hr. 10 min. | 2 min. 41 sec. |
| Cold water (1 c. water) | 1 hr. 10 min. | 2 min. 40 sec. |
| Salt water (1 c. room temp. water + 1 tbsp. salt) | 1 hr. 50 min. | - |
4. Show data of experiment repeated
| | Freezing time | Boiling time |
| Hot water (1 c. water) | 1 hr. 7 min. | 2 min. 40 sec. |
| Cold water (1 c. water) | 1 hr. 7 min. | 2 min 39 sec. |
| Salt water (1 c. room temp. water + 1 tbsp. salt) | 1 hr. 46 min. | - |
5. List your controlled variables for your experiment
Same source of water (Menomonie tap).
Same area used in the same freezer.
Same burner used on same stove. The burner will continuously stay at the same temperature.
Same pot used to boil the water. The pot will be at about the same temperature when I start.
Same container used to freeze water.
On all experiments, I will consider the water freezing when the top layer of the water is solid.
On all experiments, I will consider the water boiling when I see many bubbles rapidly coming to the surface with steam.
6. Formulate a theory that answers the questions posed.
When boiling regular water, it doesn’t matter what temperature the water is at the start because the water will boil at the same time in the end.
The temperature of the water doesn’t affect the length of freezing time. At first, the water will freeze on the top and then throughout the container. The water will eventually freeze to a solid.
At the beginning, salt water will freeze slower than regular water, but it will be frozen more throughout, like slush.
7. Image of the atoms that make up water molecules.
Observation/ Ask a Question
(This is where you are to state your observation and the question that you have.)
Is there a change in boiling and freezing time if you use cold water, hot water, or salt water?
(This is where you state what you think will happen before you do your experiment.)
The hotter the water, the faster it will boil. The colder the water, the faster it will freeze.
Room temperature salt water will freeze slower than room temperature regular water.
(This is where you actually do the experiment to test your hypothesis.)
Rules:
When boiling water, I will make sure that the burner is fully hot before I set the pot of water on the burner. I will then set the pot filled with the water on the burner. I will start my stopwatch when I set the water on the fully hot burner. I will consider the water boiling when I see many bubbles rapidly coming to the surface with steam. I will then stop my stopwatch and record the time. I will then start the next boiling session on the same burner with a cooled pot to make sure that the pot is the same temperature when starting each time.
When freezing water, I will fill each container up with the water and then I will set them in the freezer without a cover. I will then start my timer. I will consider the water frozen when I see that the top layer of water is frozen. I will then look at the time on the stopwatch and record that time. I will let the stopwatch run until all types of water have frozen.
When boiling water, I saw that it didn’t matter what temperature the water was in the beginning because they would both start to boil at approximately the same time.
When freezing water, I saw that the temperature didn’t matter either. Both the warm and cold water froze at the same time. The salt water took longer to get to the same state that the regular water was at.
(This is where you state if your hypothesis was right or not.)
When boiling water, I saw that my original hypothesis was wrong because I thought that the warm water would boil faster than the cold water, but they actually boiled at the same time.
When freezing water, I saw that my original hypothesis was correct.
(This is where you would change your hypothesis from what it was before to what you think it will be now.)
No matter what temperature you start with, water will always boil at the same rate.
The room temperature salt water will take longer to freeze than the non salt water.
(This is where you would redo the experiments to test your new hypothesis.)
When doing the experiments again, I saw that I got the same times on the warm and cold water, which was odd because usually they are off a bit. When you think about it though, water is water and it will reach its boiling point at the same time as before if you have the same variables.
Again, the salt water did take longer to freeze.
(This is where you would state that your new hypothesis was correct and it is supported by your data.)
The second time doing these experiments, I found pretty much the same results except for the fact that the times were a bit less on everything.
(This is where you would state your theory about your experiment and its data.)
Regular water will boil at the same rate no matter what the temperature is. Regular water will freeze at the same time no matter what the temperature. Salt water takes longer to freeze than regular water.
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