Can anyone do the answers to the exam?

[Jdog]

I agree, i assumed
the ethanol had all reacted to form ethyl stearate

[cltf]

In question 8, as it didn't say what is the structure of ibuprofen lysine in water....can you have C?

Thanks for the answers being put up so quick too!

Thats the dilemma pretty much, we'll just have to wait and see

[lilaznkev1n]

1.A
2.B
3.C

SA
q4
a) 36.8%
b) Percentage stays the same, because the H20 lost is proportion - mass and molar mass will decrease

OMG! if it is the same imma lose 4+2= SIX MARKS!!!! on that question....
i wrote lower cause heating will make sure no water remains therefore lower mass of precipitate there lower percentage...

[stonecold]

This may seem like a stupid question... but ... question 9 MC...

The layers one... wasn't all the ethanol used up in making the biodiesel?

I think you can assume there is excess ethanol

But what if there wasn't? It doesn't state that there is excess...

I am hoping that it wasn't in excess because I said it wasn't in the layer.

They might have to accept both. If it is COMPLETELY converted without stating ethanol is in excess they can't expect people to know it's in excess UNLESS THEY BOTHER SAYING IT!!!!!!!!!!

I see where you are coming from, and I hope for your sake they do, but when the reaction goes to completion, it is pretty much certain that an excess of reactant is used.  There is no way you would try to synthesize something using exact amounts.

[illuminati]

I think esterification reaction is partially reversible, so I did excess ethanol as well

[jane1234]

In question 8, as it didn't say what is the structure of ibuprofen lysine in water....can you have C?

Thanks for the answers being put up so quick too!

I got C too
If they were going to show that there was ionic interactions in water then you would think the COOH on lysine would be in the zwitterion state and it would be COO-. But it doesn't say show that. How can half of it be ionised and not the other half in a neutral solution?

EDIT: Stonecold that's unit 4 though... =.= They can't expect us to know that!!!!!!

[dakes112]

does anybody have the answers to the short answer sections?
thanks

[luken93]

I came from the approach that they were assessing our knowledge of the production of biodiesel, hence layer A is only biodiesel, and layer B are the by products of the conversion, hence KOH and glycerol...

[Syaoran74]

Question 9 is D??
can anyone explain that to me, i thought all the ethanol went into making the biodiesal

[jane1234]

I came from the approach that they were assessing our knowledge of the production of biodiesel, hence layer A is only biodiesel, and layer B are the by products of the conversion, hence KOH and glycerol...

So you put A as well?
If you put it they can't mark it wrong

[Christafa]

I came from the approach that they were assessing our knowledge of the production of biodiesel, hence layer A is only biodiesel, and layer B are the by products of the conversion, hence KOH and glycerol...

So you put A as well?
If you put it they can't mark it wrong

I can't remember what the letter was, but it was the one without ethanol and just KOH and glycerol. Was that A?

[jane1234]

I came from the approach that they were assessing our knowledge of the production of biodiesel, hence layer A is only biodiesel, and layer B are the by products of the conversion, hence KOH and glycerol...

So you put A as well?
If you put it they can't mark it wrong

I can't remember what the letter was, but it was the one without ethanol and just KOH and glycerol. Was that A?

Yeah.

Also, as much as I wish 18 WAS C... isn't it B?

[cltf]

Question 9. Is not worded too well, but as a general consensus, if all the canola oil is converted, then the ethanol must be in excess or exact. However, VCAA is implying that the canola oil is the LIMITING REAGENT, by stating it COMPLETELY reacted, therefore, ethanol is in excess.

[lilaznkev1n]

18.C


I have not done this type of stuff for a long time guys so I cannot guarantee they are all correct.

Let me know if there is an error

Question 15 seems to be correct.

For question 18 I got C as well by my teacher says its B so I'm not sure.

[jane1234]

Question 9. Is not worded too well, but as a general consensus, if all the canola oil is converted, then the ethanol must be in excess or exact. However, VCAA is implying that the canola oil is the LIMITING REAGENT, by stating it COMPLETELY reacted, therefore, ethanol is in excess.

But unless they explicitly state that, they can't expect people to know. Hints aren't enough.