12 replies to this topic

[someone11]

I went over it with my chem teacher.


The use of the plastic bag was to CONDENSE WATER VAPOURS
It was addition polymerisation


any other question?

oh and for the record usually in chemistry, especially with questions on experiments, there is usually only one purpose.

[ginneswatson]

You couldn't eleborate could you. Did your teacher say why the bag would need to condense water vapour?

In the old days, the police used this system as a roadside check. The phrase 'could you blow into this bag, sir' became famous. When asked why, the police would say 'because my chips are a bit hot', or so comedians used to tell us.

Anyway, one way of trying to cheat the old breathalyser was to only pretend to blow. The bag is there to stop that. You had to blow until the bag was full.

Not that I was ever breathalysed, you understand

[d00pyd]

You couldn't eleborate could you. Did your teacher say why the bag would need to condense water vapour?

In the old days, the police used this system as a roadside check. The phrase 'could you blow into this bag, sir' became famous. When asked why, the police would say 'because my chips are a bit hot', or so comedians used to tell us.

Anyway, one way of trying to cheat the old breathalyser was to only pretend to blow. The bag is there to stop that. You had to blow until the bag was full.

Not that I was ever breathalysed, you understand

That's the exact reason I gave - to make sure that the person wasn't cheating!

[Michael]

That's the exact reason I gave - to make sure that the person wasn't cheating!

In the exam, wasn't it a self test kit? Why would they cheat themselves.

[ginneswatson]

Fair enough about the cheating.

But I still feel you would want to have a minimum volume of breath going through the tube.

[Michael]

Fair enough about the cheating.

But I still feel you would want to have a minimum volume of breath going through the tube.

Yeah you would otherwise the reading would be completely inaccurate. Personally I think there will be various answers to that question.

[d00pyd]

That's why I put the exclamation mark - I agree it was a ridculous answer!

[someone11]

nonono. not to disallow cheaters. It was to make the test more reliable, its harder to test a gas than a liquid.

[Nathan]

nonono. not to disallow cheaters. It was to make the test more reliable, its harder to test a gas than a liquid.

I would say no to that too....i would say that it was to get the same volume each time and therefore the test is valid.

[ginneswatson]

I've maybe confused things here. When I was talking about 'cheating' I was only talking about the old breathalyser as used by the police. I wasn't suggesting that that was a reason for having the bag in the context of the exam question.

For the exam question, I think, the bag ensures that a decent volume of air has been blown over the crystals to make it fair, reliable, repeatable, consistent, .......... take your choice.

[sarmad]

I've maybe confused things here. When I was talking about 'cheating' I was only talking about the old breathalyser as used by the police. I wasn't suggesting that that was a reason for having the bag in the context of the exam question.

For the exam question, I think, the bag ensures that a decent volume of air has been blown over the crystals to make it fair, reliable, repeatable, consistent, .......... take your choice.

i wrote so that the air mixture doesnt escape, also that it has been oxidised resulting in it forming an acid and therefore can not be allowed to escape as it could be dangerous. Is this a wrong answer???

[ice_illusion]

I've maybe confused things here. When I was talking about 'cheating' I was only talking about the old breathalyser as used by the police. I wasn't suggesting that that was a reason for having the bag in the context of the exam question.

For the exam question, I think, the bag ensures that a decent volume of air has been blown over the crystals to make it fair, reliable, repeatable, consistent, .......... take your choice.

i wrote so that the air mixture doesnt escape, also that it has been oxidised resulting in it forming an acid and therefore can not be allowed to escape as it could be dangerous. Is this a wrong answer???

Theres probably going to be a few million answers accepted for that one. Not allowing the air mixture to escape could be ok.

[someone11]

who cares actually. it was only worth 1% of your mark. enjoy your summer yall