Exam Suggested Solutions

[equinox]

well i put that it is made by yeast..well enzymes from yeast and that it comes from glucuse or whateva in an attempt to cover both bases.  hopefully i get marks for this.

[csq7]

LOL i can if you buy me a decent computer that doesnt disconnect every frikking 5 minutes and hangs every half an hour thanks for the solutions

[Charbel]

ok this is what i did....

i looked at the graph saw that we need 80ml of 0.1M solution... 0.08x0.1= 0.008 then said.. ok we need 25 times the amount... = .2mols....

please explain what i did wrong.. i understand i could of taken the mass o.0 but why did this way fail also ?

[Charbel]

im starting to think my estimation of 80ml was inacurrate o.0

[ben4386]

with the biochemical fuels thing, did any of you actually mention that it is indeed a fuel, this seems a big part of the question i.e. mentioning that it can be blended with petrol and used as fuel to power vehicles, (E10 known as 10% ethanol blended with 90% petrol)

[csq7]

hmm yes thats a good point but it was worth one mark and i think the most obvious thing was that it came from plants.

[jay.]

grrrr what an impossible exam screwed up so many questions
thank god i didnt waste time studying for it

[Mao]

with the biochemical fuels thing, did any of you actually mention that it is indeed a fuel, this seems a big part of the question i.e. mentioning that it can be blended with petrol and used as fuel to power vehicles, (E10 known as 10% ethanol blended with 90% petrol)

part one of the question

it was already stated that ethanol is a fuel.

that section of the question deal with why "bio" rather than why "fuel"

[Mao]

ok this is what i did....

i looked at the graph saw that we need 80ml of 0.1M solution... 0.08x0.1= 0.008 then said.. ok we need 25 times the amount... = .2mols....

please explain what i did wrong.. i understand i could of taken the mass o.0 but why did this way fail also ?

I dont think that'll award marks, as the method is wrong [so is the solutions]

this is a gravimetric analysis. by principle, you should not use the volume of the precipitating agent in your calculations as it is always in excess.
volumes are used for calculations in volumetric analysis.

It is clear that 2.0g of precipitate formed, hence the process of converting that to no. of mols -> original sample -> mass -> %mass

technically it is possible to get the exact volume, but in this case it was definitely an estimate, hence wrong.
[however, you may be awarded consequential marks for the next questions]

[Charbel]

just wait and see how mean the marker gets =\ i dunno it was the first question i did..

bit nervous and all.. just fell into the trap.. of omg... molarities must be volumentric.. LOOk a 0.1M..

over thought that one.

everything else seems ok but... i made one mistake with reductant.. i stated the reduction path >.>

And im not sure about the naming.. like.. ethylamide... aminoethane... hmm wait it out.

[bucket]

with the biochemical fuels thing, did any of you actually mention that it is indeed a fuel, this seems a big part of the question i.e. mentioning that it can be blended with petrol and used as fuel to power vehicles, (E10 known as 10% ethanol blended with 90% petrol)

Lol wtf why would you repeat what they said?
I think the two important points would have to be have been that they are made from natural processes, and that the sources (ie. glucose) is renewable.

The thing thats wrong with your answer, is that biofuels include biogas and biodiesel aswell, which is not 'known as 10% ethanol blended with 90% petrol'.

[Rosie]

Calculating from Mao's answers I got 48. What do you think this will be, a C or C+.

[jay.]

ooo 62% a safe C i reckon


id get around 70-72% what do you reckon that would get me

let me clone you mao

safe C+ i meant

[ilovenmr]

that was really really really really really really really reall hard

if i didnt do biology last year i would have failed miserably

slash i probably still will

this was a crazian exam!!

[infraredismybitch]

the molecule is called 3-chloro,6-methylheptane!
i honestly dont think i dropped a mark!!
only coz i owned biol last year though
 nooobs