data booklet

[khalil]

i was wondering to which sections do we have to be familar with in the data booklet.. cause i wanna get familar with the concepts , but not sure which ones are relevant to unit 3

also... in 2008 exam mc Q4
 in the data booklet it states: colour change Acid Base............... for the colours it shows for each, does that mean the colour is the one that changed, or its the original colour of that acid or base???

okai.. thx for the answer.. another question..... when writing systematic names do you need to place a -.. for e.g 2 methyl propanol.... that's how i write it, but in vcca assemeents it's like
2-methyl-1-propanol so if i don't put those dashes, is it considered wrong??/

[Toothpaste]

The end point is observed at pH of ~6 - 11
Go to the data booklet and you'll be able to say methyl red can't be used (pH range is 4.2 - 6.3)
That leaves phenolphthalein which is colourless when acidic, red when basic.
You are adding weak acid acetic acid to NaOH a strong base.
so it starts off as basic and changes to acidic.
therefore red to colourless.

In regards to your question, it's the colour at what the solution is (acidic or basic)
Er, like if you were using phenol red in an acid it would be yellow at first. Adding a base to the solution with the phenol red+acid and reaching the end point would give red, as it has now turned slightly basic.


For Unit 3 I remember using these:
Periodic table
Physical constants
NMR data (H and C)
Infared
Amino acids
Fatty acids
Structural formulas of some important biomolecules
Acid-base indicators

It's not necessary to memorise anything, but you'll find you'll start doing it anyway


Periodic table: lol, self explanatory.

Physical constants: most of these are memorable and you probably know them off by heart. It's just there in case you get brain freeze. Stuff like Faraday's constant and spec. heat of water are in unit 4.

NMR, Infared: These you'll have to know what they're for and how to match graphs in the exams to them. For optimum pwn, do heaps of questions that require use of the tables so that you know where to look for specific structures.

Amino acids: for drawing, identifying R groups, etc. (I think I ended up remembering the structure and corresponding names for ~9 of them ... it was an accident haha.)

Fatty acids: all I remember using this for was in one of the MC questions in the exam. It was at the end somewhere.

Structural formulas of some important biomolecules: for when you finish the exam 30 minutes early due to major awesomeness - stare at sucrose and think: hey I'm gonna go buy some skittles afterwards. (HOW CUTE IS SUCROSE!!!!)
Nah I kid you. Notice how they don't give you both deoxyribose and ribose, this means you have to know the difference (one's missing the OH). Know how to draw glucose. Sucrose is the disaccharide of glucose + fructose and it's given. Try separating the glycosidic bonds and reforming the monosaccarides in your brain.
There's not a lot they can ask about these to be honest :\

Indicators: ;p not much to learn here. Your question is an example of where it can be used.

[khalil]

oh coo.ll thx alot,, it's all cleared up now...
another questioon..........on MC Q19 how would u do that///??? 2008

[Toothpaste]

oh coo.ll thx alot,, it's all cleared up now...
another questioon..........on MC Q19 how would u do that///??? 2008

Ah, the fatty acid one. That's where the table comes into play a bit.

You only need data for these:
A. lauric.
B. linoleic.
C. palmitoleic.
D. arachidonic.

Go to the table and find them.

Lauric
Linoleic
Palmitoleic
Arachidonic

0.150 mol of a particular fatty acid reacts with exactly 0.300 mol of .
Ratio time-

Fatty acid :
0.150 mol : 0.300 mol
1 : 2

When molecular iodine, , reacts with an unsaturated compound, one molecule of iodine adds across each double bond. Unsaturated fatty acids react in this way with iodine.

There are two double bonds in our fatty acid under inspection (the ratio says so, as "one molecule of iodine adds across each double bond" and we used two molecules of iodine for one molecule of fatty acid)

In the exam I had plenty of time and ended up double checking this one by drawing the structures out.
What you want is
an unsaturated fat with
2 double bonds between carbons.

You can use the fatty acid formula and tweak it (I think this is on the assessment report, do you get that solution? Or should I explain it?), or draw them out to have a look (takes longer I think. I just visualised the molecules in my brain during the exam then came back later to check/draw).

I feel like drawing. I haven't drawn for VN for a while.

lol at fat hydrogens.
Lauric is saturated, no double bonds. Therefore we ignore it.

Next guy linoleic acid:

OH HEY IT'S THE ANSWER.
First you would draw all 17 +1 carbons.
Add the carboxyl functional group at the end.
Count how many Hydrogens you'll need for the form without double bonds (in this case it was 35).
Look at how many H we actually need. (we need 31 in there)
35 - 31 = 4, we need to get rid of 4 hydrogens by making the molecule unsaturated.
When you add a double bond 2 hydrogens are taken off; Carbon only forms four bonds.

Here's a diagram that popped into my brain while I typed that sentence before:


If you work out the last two, they don't have 2 C=C bonds.

This question isn't as long as I made it out to be, just so you know.

[khalil]

okai.. thx alot for the answer... u cleared itup for me thx....sorri that it took so much of ur time... but anotherr.. ..... when writing systematic names do you need to place a -.. for e.g 2 methyl propanol.... that's how i write it, but in vcca assemeents it's like
2-methyl-1-propanol so if i don't put those dashes, is it considered wrong??/

another question

Q4 ci.... chem 2008...................... it asks what information can be deduced from abvove spectra....... the answer is a carbonyl group, but they also write it as  + C=0... where did the plus come from>?

Q5i.... when writing the structure.... i write it     H-C-H......... but in vcca assesment report, they write it kind of slanted to a degreee sort of thing... would my straight chain be alright???

[Toothpaste]

okai.. thx for the answer.. another question..... when writing systematic names do you need to place a -.. for e.g 2 methyl propanol.... that's how i write it, but in vcca assemeents it's like
2-methyl-1-propanol so if i don't put those dashes, is it considered wrong??/

Put the dashes in! (IUPAC says so, and always follow the reports). Personally I would consider no dashes wrong. (You might get a pedantic examiner too)
Else it's like saying I have two methyl propanol things, instead of this is 2-methyl-1-propanol. Or something trivial like that, if you get what I mean. haha

Q5i.... when writing the structure.... i write it     H-C-H......... but in vcca assesment report, they write it kind of slanted to a degreee sort of thing... would my straight chain be alright???

Yeah straight chain would be alright in VCE. I did straights sometimes too.

Slanty kinds save more space and are more prettier.

Also... further learning can start by googling: VSEPR theory, chirality ... if you're bored and want to discover the magical world of molecular bonding/shapes/awesomeness.

okai.. thx alot for the answer... u cleared itup for me thx....sorri that it took so much of ur time...

No worries, I'm just procrastinating from doing uni chem. So this is somewhat productive ...

[khalil]

what about the other questions??? and also.. is an alkyl group a functional group??? refering to 5ii............. as it only states o-h.... in asnwers