Why Is There Vapour in Dry Ice Experiments?

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    Co2 Vapour
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Discussion Overview

The discussion revolves around the process of sublimation of dry ice (solid CO2) when placed in water, specifically focusing on the generation of bubbles and vapor during the experiment. Participants seek to understand the underlying mechanisms and safety considerations for demonstrating this phenomenon to a children's class.

Discussion Character

  • Exploratory
  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant inquires about the process of sublimation of dry ice in water and expresses a desire for a simple yet accurate explanation suitable for children.
  • Another participant explains that CO2 sublimates due to temperature and pressure conditions, noting that the dry ice sublimates more rapidly in water than in air. They clarify that the bubbles are gaseous CO2 and that the visible vapor is actually condensed water droplets, not gaseous CO2.
  • A suggestion is made to use flavored drinks like kool-aid or grape juice to enhance the demonstration, along with a warning about the risks of frostbite from skin contact with dry ice.
  • One participant provides a density comparison between solid and gaseous CO2, indicating that the volume of gas produced from a given volume of dry ice is significantly larger, which contributes to the observed bubbles.

Areas of Agreement / Disagreement

Participants generally agree on the basic process of sublimation and the nature of the vapor produced, but there are variations in the explanations provided. No consensus is reached on the simplest way to explain the phenomenon to children, as different approaches are suggested.

Contextual Notes

Some participants express uncertainty about the best way to communicate the scientific concepts to a young audience while maintaining accuracy. There are also considerations regarding safety when handling dry ice.

Who May Find This Useful

This discussion may be useful for educators, parents planning science demonstrations, and individuals interested in the physical properties of gases and sublimation processes.

turtleluc
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Homework Statement



Hi there, could anyone help me pls. I want to show my sons kinder class what happens when you put Dry Ice (solid CO2) into water but would like to know for them and for me what the actual process is when it sublimates. I don't understand why there are so many bubbles or even why there is a vapour. I need to make it extremely simple for them but think an acurate explanation is important and I love these things myself so would like to know as well. Also, is there anything I should be careful of, I am going to buy a kilo as that is the smallest amount I can purchase and pop it in a glass jar. Thanks so much for any help you are able offer.


Homework Equations





The Attempt at a Solution

 
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The CO2 sublimates because the temp and the pressure of the surroundings. CO2 can be liquid, but requires conditions of temp. and pressure that we do not normally encounter. When you put dry ice in water, it sublimates more rapidly at first because the room temp water is heating the CO2 more rapidly than if it was just in room temp. air. The bubbles are gaseous CO2. The CO2 is not all going to dissolve in the water, especially considering that water is much more polar. The vapor you see is actually just like fog. Its water in the air condensing out into tiny droplets because the dry ice has cooled it so much the water condenses into these little droplets. So The vapor you see is not gaseous CO2 its water. This is my understanding anyways. and it makes sense to me.
 
Thank you so much for your help! I really do appreciate it. I think the kids should really enjoy it (I do)
 
Do it with kool-aid or grape juice, and lots of sugar, and you'll have soda pop!
http://www.wikihow.com/Carbonate-a-Beverage

Make sure to avoid prolonged skin contact with the dry ice, though, it can give you frostbite.
 
MATLABdude said:
Do it with kool-aid or grape juice, and lots of sugar, and you'll have soda pop!
http://www.wikihow.com/Carbonate-a-Beverage

Make sure to avoid prolonged skin contact with the dry ice, though, it can give you frostbite.

thanks very much for your advice, if I can get some dry ice today I will be taking it in and will try your suggestion, thanks!
 
As far as why there are so many bubbles, gaseous CO2 has a much lesser density than solid CO2
1.562 g/mL (solid at 1 atm and −78.5 °C)
1.977 g/L (gas at 1 atm and 0 °C)

Notice, that's more than 100 times the density. In other words, for every mL of dry ice you place in the water, you will get more than one liter of CO2 gas.
 

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