Prac - decarbonating soft drink (2 Viewers)

[nesstar]

I was looking at the prac we did, and we just let the soda water sit and decarbonate...we didn't do anything to it. Is this acceptable?
I was looking at the csu site and they were saying the 2 methods were heating and salting...so i wasn't sure if i should change mine?

 

[Tommy_Lamp]

What we did was open the top very slowly, letting the gas escape gradually until no more sound of gas escaping was heard, so yeah i think its acceptable.
and remember, if it works, its acceptable

 

[nesstar]

thanks heaps!

 

[tennille]

Yeah, it really doesn't matter. As long as most of the gas is released, then it should be okay. We placed a can of coke in hot water so the gas is released faster.

 

[Tommy_Lamp]

I think the whole aspect of heating is used to speed up the reaction, like Tennille said, making it more suitable for a class experiment (i.e. 80min lesson, sometimes 40min). if the Q specifically asked for your prac in a class room, or regards a student doing it in a classroom, it would be good to add "heating" because of time constraints etc.

 

[Li0n]

not only that, puting other stuff to increase the release of CO2 will show the marker than you know which factors affect the solubility of CO2 in water or whatever...

ah meh i dont think it matters too much as far as marks are concerned anyway

 

[tina_goes_doo]

I never got to do my prac. My partner shook the can up, tapped it a few times with a metal spoon and then opened it. Lemonade went everywhere so he drank it.

Bastard.

 

[mr EaZy]

we all left our cans overnight.
i came back the next day, but someone drank from my can: it was all gone!

how much gas is actually in a 370ml can anyway? i made up my resluts and got 10/10 for some reason.

 

[steph@nie]

as long as you show weight to a constant mass, it doesnt matter.

 

[jumb]

I never got to do my prac. My partner shook the can up, tapped it a few times with a metal spoon and then opened it. Lemonade went everywhere so he drank it.

Bastard.

Yeah I heated our's up. It went over 100oC (therefore losing water aswell) and it was splashing everywhere. Of course I'm the sort of person that would do a titration in a beaker (thats too small), accidently poor heavy metals down the sink and break stuff.

I'm gonna miss school.

 

[tennille]

i ended up with like 0.15L but it's probably wrong. I don't know what the volume is meant to be.

 

[t-i-m-m-y]

the volume is irrelevant. in the sense that they aren't going to ask you to quote your answer. learn the chemistry ie the equation/equilibrium behind this prac, and know how to do the calculations.

 

[bobbie212]

i wonder, if you had a control filled with water and measured the mass loss due to evaporation, could u then take this away from the mass loss of the soda water to find the real loss of carbon dioxide?

 

[Xayma]

Yes. As long as they have the same surface area. We did it tons of ways so each group did it differently and we could see factors associated with it. We even depressurised it in a bell jar, added HCl to push the equilibrium towards it coming out of solution etc.

 

[lukebennett]

i think mentioning salting would be a good idea if you dont have much time. you need to mention that the CO2 escapes quickly because the ions in the salt bont more readily to the water molecuels than the CO2 does so the gas is released.

 

[Tommy_Lamp]

lukebennett: i dont think thats necessary

 

[tennille]

It shouldn't be necessary. It doesn't mention a specific method in the syllabus. As long as the gas escapes, it should be okay. I just put it in hot water to speed up the reaction. The aim of the experiment is to determine the volume of CO2.

 

[jumb]

The equilibreums are easy!

1) co2 becomes (aq)
2) that reacts with water
3) then lose 1 h+
4) then lose the other h+

 

[persephone]

my prac was we transferred the soft drink into a larger bottle. weighed it, then shook it for a while then it got hazy. my group didn't get to do it because when we opened our bottle of coke it came pouring out, so it wouldn't have been accurate. we then spent the rest of the lesson playing the blame game

 

[Paroissien]

I suggest in the HSC you put a step in where you either heat it (better) or add salt (crapper). There is more chemistry involved in those methods than simply shaking it, which is a good thing