Hot vs Cold Water Experiment (Chemistry)

In this experiment, you can visualize the difference in density between hot and cold water. Using the food coloring and a thermal infrared camera you can really see what is happening at the particulate level.

▶️ Hot vs. Cold Water Density Experiment Procedures:
Step 1: Gather supplies--two glasses of the same size, a hard piece of plastic, and two different colors of food coloring.

Step 2: Fill one glass with cold water to the brim, so the water is bubbling over the top of the glass.

Step 3: Fill the second glass with hot water to the brim as well.

Step 4: Stir in food coloring to the cold water. Mix well. I used blue for the cold water.

Step 5: Stir in a different food coloring to the hot water. Mix well. I used red for the hot water.

Step 6: Place the thin, flat plastic on top of the hot water glass so you can flip it upside down without spilling the water.

Step 7: Carefully turn the hot water glass upside down, holding the plastic in place, and set it directly on top of the cold water glass. Make sure the rims line up all the way around.

Step 8: Carefully remove the plastic from between the two glasses to allow the water to mix, and observe.

▶️ How the hot vs. cold water density experiment works:
You'll notice that the hot and cold water don't mix after the plastic piece is removed, with hot water staying on top and cold water staying on the bottom. That's because the density of the cold water has particles packed a little closer together than the hot water, and gravity is pulling them down now. it's time to repeat the experiment only this time we're going to reverse it so go ahead and fill up your cups with hot water and cold water again and then use the food coloring to make the hot water red and the cold water blue

Try reversing the experiment with the cold water on top instead, and you'll see the cold water and hot water start mixing quickly. This is because the higher density cold water starts falling down through the lower density hot water. The temperature of the hot water stays hot and the temperature of the cold water stays cold.

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[wheresthepizza]

Crazy story but true. I’ve dreamed and pondered about this exact experiment for years but never actually looked it up to see if someone did it. I found this within 5 minutes of searching. What a great experiment! Thank you for the fantastic visuals and thermal views. Thank you for posting this.

[yeelingleong]

This is excellent teaching material - clear, concise and well-structured. Thank you :)

[vkira]

yes u makeing more videos now r the best

[alethaprice]

Perfect... thanks for sharing! My students will enjoy doing it.

[VinitBavishi]

Why do you put only 1 drop of blue color and multiple drops of red color? Just curious if it is on purpose or just by chance.

[juandelacruz]

Question my friend: They say heat desires to move toward the cold, right? If so, in the first test, do you think the heat or hot water desired to move toward the cold, but was prevented due to the density factor of the cold water underneath being more dense? What about in the second test? Did the heat or hot water desiring to move toward the cold water above play a factor? I understand the density part, but it would seem that the heat or hot water would be a factor in the movement of water from one to the other, right?

[ecospider]

How much salt would you need to add to the hot water to make it denser than the cold. I want to show my niece that it is not Heat that rises. It is less dense liquids rise and hot water is usually less dense but not always.

[Tylerson]

MOAR!


Great to see you back, my dood!

[lame]

Thanks for the view after 10 minutes.
So there IS a heat convection / transfer.

Someone tried to tell me that hot water in a boiler will remain hot, if you take some hot water from top and fill it up with cold water from below.

[lilsnipemike]

My school teacher is doing a test in this

[allinoneig]

I have seen many videos and all those were nice and it worked. But Which app is used for the thermal camera??

[ChillkittzGT]

Thanks for the experiment! my sibling have this experiment as their science project, and I stumble upon your video. Now me and my sib know the full procedure of the experiment and it ended up pretty well. thanks again!

[SunnySingh-gsqy]

Why you did not post video regularly love from India😍😍

[Gabo]

Loving the content, BSG
Keep em coming!

[snakeeva]

I understand why the colors don't mix in the case of hot water atop cold water, due to the difference in densities. However, I'm really puzzled about the temperatures not reaching equilibrium on the thermal camera even after 10 mins? Thermodynamics dictates that heat flows from hot to cold body. Even if no heat was flowing between the hot water and the cold water in the glasses, both glasses would be losing heat to the environment and thus the temperature should drop (hot) or be risen (cold) in both glasses. Based on thermodynamics the video is not making any sense. Please explain, using thermodynamics equations if possible, what is happening on the thermal camera when hot water is placed on top of cold water. If this were possible then it seems that the second law of thermodynamics would be violated.

[julierobledo]

I like the content very much, but the music is so loud and

[IBAlexanderIB]

"hot water" and "cold water" ok, but... how cold and how hot?.. For all I know it is 20c and 40c water. It is weird to me that you don't think about informing about that before in the middle of the video. Cool experiment though.

[jereelylopezhernandez]

Hot + cold + water = hot water. Then blue + red.🤒

[jonathancollins]

What happens if both jars of water are at the same temperature?

[marwadjerafi]

Sir im sorry to bother you i just didn’t get it well
U were saying that the density of cold water has what....?