decarbonating sogt drink (using salt or heating?) (1 Viewer)

[tango400]

I want to ask whether using sodium chloride or heating the soft drink would be more effective (or both?). Also, what does each of them actually do for the carbon dioxide gas to be released? What does the salt specifically do?

 

[Riviet]

I want to ask whether using sodium chloride or heating the soft drink would be more effective (or both?).

Heating the soft drink is ineffective because you lose alot of the solution due to evaporation of the steam created by heating. You want to keep all your solution to be as accurate as possible. However, if you are asked to do the prac by heating, you should heat to about 40 degrees or so and stir it until all the visible bubbles disappear. That's all I know which is correct, I'll let someone else answer your other questions.

 

[Dreamerish*~]

Adding NaCl will reduce the solubility of CO₂. I don't know exactly why.

However, it's not recommended for this prac because your aim is to find the difference in mass caused by the loss of CO₂. Adding salt will interfere with your mass measurements and produce a result that isn't valid.

Heat is an effective way of removing CO₂, although you should know that it would be dangerous to heat the plastic bottle directly above a flame. A heating pad is a good alternative, as is a water bath (not boiling water). Keep in mind that for the sake of accuracy, you should not transfer the liquid to another container. Keep the soft drink in the bottle at all times, and take extra care to prevent spillage or evaporation.

For more information on this prac, have a look at the following BoS threads:

http://community.boredofstudies.org/240/acidic-environment/90108/decarbonation-soft-drink.html
http://community.boredofstudies.org/240/acidic-environment/102312/decarbonating-soda-water-prac-help.html
http://community.boredofstudies.org/240/acidic-environment/101471/shaking-carbonated-drinks.html

Also the following websites:

http://en.wikipedia.org/wiki/Solubility_pump
http://www.geocities.com/jamesyscience

Other important information about this prac can be found in the above links.

 

[Riviet]

The salting method is a good method as well, which is why I recall my teacher telling us to add no more than a tea spoon of salt, since the change in mass is very little and therefore neglible when doing the calculations. Obviously if you add too much salt, it will affect the mass and lead to your inaccurate calculations.

Edit: it's actually not. My bad. XD

 

[Dreamerish*~]

The salting method is a good method as well, which is why I recall my teacher telling us to add no more than a tea spoon of salt, since the change in mass is very little and therefore neglible when doing the calculations. Obviously if you add too much salt, it will affect the mass and lead to your inaccurate calculations.

The mass of CO₂ lost is usually around 1 g (in Jamesy's report it was 1.5 g), which is much less than a teaspoon of salt. The salt would cause not a negligible, but quite a significant change in mass.

 

[Riviet]

The mass of CO₂ lost is usually around 1 g (in Jamesy's report it was 1.5 g), which is much less than a teaspoon of salt. The salt would cause not a negligible, but quite a significant change in mass.

Thanks for pointing out. I didn't know that there was that little CO₂ in terms of mass. I guess the heating method yields more accurate results.

 

[tango400]

I just want to make sure - With the heating method, i need to keep the lid off rite?

 

[Dreamerish*~]

I just want to make sure - With the heating method, i need to keep the lid off rite?

Yes. You want the CO₂ to leave the bottle.

 

[(enigma)]

actually as long as you weigh the amount of salt before its added then you shouldnt have any problems. it would also make the measurements of gas more accurate, unless ive completely misunderstood how it works.