Exam Suggested Solutions

[doboman]

What was the exam out of?

[nathankb]

would they take off marks if you showed S-S bonding but were stupid and put in negative valencies?

[nathankb]

exam out of 78 by the way

[Mao]

I was about to say, I answered D for that question. There is a sixth isomer in which one Carbon has four carbons coming off it surely?

Sorry, the question required the isomers to have "a double bond." The sixth one I was thinking of was cyclopentane, which doesn't have a double bond.

There is no carbon that has four methyl groups coming off it, because then it would be C5H12. A double bond cannot be placed anywhere, as it would force the central carbon to have 5 bonds.

there are more

methylcyclobutane
ethylcyclopropane
dimethylcyclopropane

[nathankb]

i think the answer to question 7d is wrong: it asks for m/z of 45, the O in OH is 16...

[Mao]

I need help...........


You know the question where it said why ethanol dissolves in water and petrol?

Well i said Because the OH bond forms a hydrogen bond in water and the non polar end of the hydrocarbon interacts with the non polar part of petrol.
But this is where i screwed up, for some stupid reason i also added that its a dipole dipole at the end.
Now i answered the 2 points correctly, however i added something wrond and irrelevant(dipole part) to it do i lose marks for adding something wrong to something that was right? The question was 2 marks btw.

you would lose a mark, yes.

[Mao]

i think the answer to question 7d is wrong: it asks for m/z of 45, the O in OH is 16...

but i said "H" in OH

[polky]

mao: shutup that doesn't even EXIST lol. it's impossible! coblin reminded me.

I lost 1 mark.  Wrote H+ for fragment instead of H (i'm a retard like that).

[vce01]

I need help...........


You know the question where it said why ethanol dissolves in water and petrol?

Well i said Because the OH bond forms a hydrogen bond in water and the non polar end of the hydrocarbon interacts with the non polar part of petrol.
But this is where i screwed up, for some stupid reason i also added that its a dipole dipole at the end.
Now i answered the 2 points correctly, however i added something wrond and irrelevant(dipole part) to it do i lose marks for adding something wrong to something that was right? The question was 2 marks btw.

you would lose a mark, yes.

the same question

what i wrote was how the OH group had H bonding with water as it was polar and how the short tail didnt prevent it from letting that occur.

just the 1 mark, yeah?

[nathankb]

be that as it may, the H in OH is only 1...

[polky]

be that as it may, the H in OH is only 1...

The molar mass of ethanol is 46 g/mol.  To make it 45 you lose 1, and only H has a molar mass of 1.

[monicak]

Do you have to state that it was the H FROM the OH? Would you get the mark if you just wrote that a H was lost?

[bucket]

I got 81% if all of Mao's answers are right =]
63/78!

[vce01]

im getting 44/78...fdsjkfskfaskldam im gonee

[Mao]

Do you have to state that it was the H FROM the OH? Would you get the mark if you just wrote that a H was lost?

i dont think so