James Ruse Trial - how it should have looked (1 Viewer)

[superhubert]

hpe so, it would make me feel slightly smarter......

 

[spice girl]

Originally posted by Ozz^E
Ummm..wat trial is that from..im talking about the James RUSE 2002 trial where Q14. is about the empirical formulas of polyethene and polyvinyl chloride respectively. In the answers spice girl gave it has 14 as B which is CH2 and C2H3Cl..shouldnt it be B which has (CH2-CH2)n and (CH2-CHCl)n.

Don't you know what an empirical formula is?

 

[aby]

oops sorry i just checked another ruse paper.. but an empirical formula has to be in the simplest ratio according to its definition, which is why b is correct

 

[Ozz^E]

ohhh..i get it..i knew there would be side-effects of not doin the prelim course properly.

Thanx

 

[utopian731]

I thought that the JR trial would ahve been harder (it was pretty easy), simply because of all the people getting 95+ that they would have to separate, well i assume that anyway, not actually knowing anyone who does chem.

we did the Catholic trial and it was so much harder, mainly because it wasnt actually about chemistry, but that alternative shit

at lwast JR trial was about chemistry! yay!


It was funny how someone said that chem is just remembering stuff. I find that its the one I have to do the least wrote learning for, chem is mostly common sense, i dunno, thats just me...

ps. is anyone here from James Ruse who's friends with Laurence Chan? He used to go to my school, great guy

 

[utopian731]

Just a question to spice girl who posted the answers to the JR multis

How is the answer to 6 B? Like i understand the logic, but i dont think chanelling the ammonia to a cooling chamber will increase yield. Cooling the reactants will increase yield sure, but once the ammonia is formed, whats the point in cooling it?

is this to prevent it from decomposing back into nitrogen and hydrogen?

i had c, increasing the amount of nitrogen gas. This is something they actually do, so i dont relaly know how that is wrong. Increasing the concentration of a reactant in a dynamic equilibrium will force it to the right, ie increase yield

help would be appreciated
thanks

 

[spice girl]

Originally posted by utopian731
How is the answer to 6 B? Like i understand the logic, but i dont think chanelling the ammonia to a cooling chamber will increase yield. Cooling the reactants will increase yield sure, but once the ammonia is formed, whats the point in cooling it?

Well, cooling will have the effect of liquifying the ammonia, removing some of it from the gaseous phase. So the pressure of gaseous ammonia will decrease, which will shift equilibrium towards the right. They won't just add nitrogen, because they'll end up with an excess of it, which isn't good for favouring products.

 

[utopian731]

thanks