Salt Water Experiment

Salt and the effect it has on water. Do you like salt? Do you put it on your food to make it taste better? Salt doesn’t just make food taste better; it can change the freezing and boiling point of water. I bet you didn’t know that! There’s a reason for that, but I’ll explain that a little later. First, let’s find out if salt can actually change the freezing and boiling point of water. To do so, we need to do an experiment. Now, if you’re going to do an experiment, you’re going to need a hypothesis. Let’s use mine. I said “if we know salt in the ocean’s water can affect its temperature, then I wondered if adding salt to regular tap water and bottled water would raise the water’s boiling point and lower its freezing point because even though the ocean doesn’t boil or freeze salt still
affects its overall temperature.” Long, I know.
If you don’t know, a freezing point is the limit water can go to before it freezes. For regular water, this is 32 degrees Fahrenheit. A boiling point is the limit water can go to before it boils. For regular water, this is 212 degrees Fahrenheit. While I did this experiment, I used Celsius. That’s what was on the thermometer. After doing the experiment, I had to research it to find out more about salt and the effect it has on water. It turns out my hypothesis was correct. Salt did change the freezing and boiling point of water. And not just the ocean and salt water is affected by this. During winter, people put salt on the icy roads to make it safer to drive on. Now you may be asking yourself “why? There is still going to be ice on the roads.” Well, that’s where you’re wrong. The ice is already below 32 degrees Fahrenheit, but putting salt on top of the ice automatically lowers the freezing point, thus melting the ice back into a liquid. This is why the ocean doesn’t completely freeze. During winter, the temperature around the world is different. But at one point or another, the temperature gets below 32 degrees. 97% of the ocean is seawater
(salt water). That 97% will never freeze. Ok, I’ll admit it. The salt water near the North and South Pole do freeze, but that’s because the temperature there is well below zero. Even in the summer.
Now you may be wondering “hey, Kamryn! How do you do the experiment?” Well, it’s pretty easy. So I added a little twist. The materials you need for the experiment are: salt, tap water, bottled water, four cups, four thermometers, a measuring cup, a stove, and a freezer. Now, we must define the dependent and independent variables. An independent variable is a variable that can be changed. In this case, it’s the water with the salt in it. A dependent variable is a variable that you measure. Now, on with the experiment! First, get out four cups. Next, put a cup of bottled water in two of the cups and one cup of tap water in the other two cups. Make sure you get exactly one cup of water. Then, put a pinch of salt in one of the cups of tap water and a pinch of salt in one of the cups of bottled water. Now is the tricky part. Pour one of the cups in a pot, set the stove to a medium, and wait until it boils. After the water starts to boil, stick a thermometer in the pot and record the data. Now, pour that boiling water into a cup and label the cup. Do this step for all of the cups of water. If you recorded the data correctly, you would see that the water with the salt in it had a higher boiling point. This is called “boiling point elevation.” Now, the water has to cool down or the data would be messed up. Why? Because hot water can freeze faster that cold water. Now that the water has cooled down, we need to freeze the water. It’s easy! Just put the water in the freezer. Make sure the thermometers are not in the water or else they’ll freeze with the water and possibly mess up the experiment. We do not want to mess up the experiment. Check on the water every hour. It’ll take some time to freeze completely. Once the water freezes, stick a thermometer on top of the ice and leave it there for 5 minutes. Make sure to close the freezer door to keep the cold in. After 5 minutes, record the data. If you did this correctly, then the data should show that the water with the salt in it has a lower freezing point. This is called “freezing point depression.” Boom! Your experiment is done. Now wasn’t that fun? Don’t believe your data is correct? Do it again. In two sentences, i’m going to summarize what happened in the experiment. We boiled and froze the water. We found out that the water with the salt in it had a higher boiling point and a lower freezing point.
Remember i was going to explain why salt affects the freezing/boiling point of water? Well, here’s the answer! Salt is a non-volatile solute. Non-volatile solutes are used to lower the freezing point of water. I found this out while researching. I also found out that sugar is a non-volatile solute and can be used to change the freezing/boiling point of water, just like salt. One thing you may not know is that salt is a common ingredient in antifreeze. Antifreeze is used to keep pipes and engines from freezing solid in the winter.
Let me restate the hypothesis. If we know salt in the ocean’s water can affect its temperature, then i wondered if adding salt to regular tap water and bottled water would raise the water’s boiling point and lower its freezing point because even though the ocean doesn’t boil or freeze salt still affects its overall temperature. During the experiment, the data proved my hypothesis correct. Why? Because, as I’ve stated before, salt is a non-volatile solute and can lower the freezing point and raise the boiling point. Scientist found this out by studying the ocean. When they found this out, they used it to the benefits of society. Now, we have antifreeze. We also use this knowledge to put ice on the roads to make it safer. If I were to research this topic even more, I would look to find out if there is anything else besides salt and sugar that could change the waters freezing and boiling point. That, and find out how it could help society even more.