ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: andy456 on June 04, 2010, 02:57:55 pm

Title: Short Answer Questions
Post by: andy456 on June 04, 2010, 02:57:55 pm
Do we need to anwer the questions in proper sentences or can we just dot point the info???
Title: Re: Short Answer Questions
Post by: Martoman on June 04, 2010, 03:03:56 pm
Depends on marks.

I usually dot point key ideas down.

If it gives a clear directive to explain or to discuss then you write in sentences. Otherwise if it says to outline stuff just dot point that bad boy.
Title: Re: Short Answer Questions
Post by: andy456 on June 04, 2010, 03:34:24 pm
Quote from: Martoman on June 04, 2010, 03:03:56 pm
Depends on marks.

I usually dot point key ideas down.

If it gives a clear directive to explain or to discuss then you write in sentences. Otherwise if it says to outline stuff just dot point that bad boy.
hahaha alright..... thanks


I have a question....
What functional group is present in all 4 nitrogen bases found in DNA??
Title: Re: Short Answer Questions
Post by: Martoman on June 04, 2010, 03:43:16 pm
I had this same question a while back.

Amine. It has its primary group AND a secondary amine .
Title: Re: Short Answer Questions
Post by: andy456 on June 04, 2010, 03:50:00 pm
Damn I worte amide..... oh well thanks
Title: Re: Short Answer Questions
Post by: Greggler on June 04, 2010, 04:12:29 pm
whats difference between amine and amide?

is amide the peptide bond eg -CONH?

Title: Re: Short Answer Questions
Post by: chansthename on June 04, 2010, 04:14:34 pm
^^yes amide is the peptide linkage
Title: Re: Short Answer Questions
Post by: m@tty on June 04, 2010, 05:49:15 pm
I get these confused too, so similar. I try and associate the d in amide with the d in peptide..
Title: Re: Short Answer Questions
Post by: Martoman on June 04, 2010, 05:51:15 pm
A-MINE is like the nitrogen saying ALL THE HYDROGENS ARE MINE (thats why he's got 2 hydrogens :))

Title: Re: Short Answer Questions
Post by: coletrain on June 04, 2010, 07:07:58 pm
can someone teach me a quick method to see whether a fatty acid is saturated, unsaturated when molecular formula is given?
Title: Re: Short Answer Questions
Post by: ghadz7 on June 04, 2010, 07:18:27 pm
CnH2nO2 is staurated

CnH2n-2O2 is mono unsaturated with one C/C double bond

CnH2n-4O2 is poly unsaturated with two carbon to C/C double bonds

CnH2n-6O2 is poly unsaturated with three carbon to C/C double bonds

See the pattern?
Title: Re: Short Answer Questions
Post by: stonecold on June 04, 2010, 07:22:37 pm
If the ratio of hydrogen to carbon is 2:1, then it is saturated.  Less than 2:1 and it is unsaturated.

Every two hydrogens less than the CnH2nO2 formula represents a double bond.

i.e. C12H24O2 = saturated (no double carbon-carbon bonds)
     C18H34O2 = monounsaturated (one double carbon-carbon bond)
     C20H32O2 = polyunsaturated  (four double carbon-carbon bonds)
Title: Re: Short Answer Questions
Post by: m@tty on June 04, 2010, 07:27:18 pm
General form of a saturated fatty acid is either: or, in condensed form, .

For every double bond there is two less hydrogens.

EDIT: removed fail error...
Title: Re: Short Answer Questions
Post by: coletrain on June 04, 2010, 07:33:53 pm
what about if they give semi structural formula?
Title: Re: Short Answer Questions
Post by: ghadz7 on June 04, 2010, 07:35:45 pm
Count the atoms then change it to molecular formula :P otherwise if theyu have CHCH that's an indication of a double bond
Title: Re: Short Answer Questions
Post by: Greggler on June 05, 2010, 12:55:09 pm
Simple little formula to work out number of double bonds..

- Make into molecular formula.
- Multiply number of carbon atoms by 2
- Subtract number of hydrogen atoms from this number.
- Divide the remainder by 2