EEK!!! citric acid drawing (1 Viewer)

[Rancid Monkey]

did you know that we are supposed to be able to draw an expanded structural formula for citric acid?
apparently its in the syllabus somewhere
i saw a question saying draw it in a trial and almost shat myself....
i know how to do it now, but how many of you can draw it without looking at a textbook?
just thought i would give you a heads-up...

formula is 2-hydroxypropane-1,2,3-tricarboxylic acid
my brilliant paintbrush rendering is below....hopefully i got it right, please tell me if i didnt....

 

[sneaker]

yeah it is pretty nasty, but try drawing some of the structural formulae in the forensic chem option!

 

[Rancid Monkey]

ahhh......the joys of shipwrecks.....

 

[crazylilmonkee]

hey i couldnt find that point in the syllabus.. is it the acidic environment one?

 

[Hotdog1]

I hope they don't ask us to draw that.

Ruse trial 2002 did had a question about the ionisation of citric acid, where you deduce the which hydrogen atoms are donated. It didn't even ask you to write the equation though.

 

[jims]

yeh its in the acidic environment:

identify acids such as acetic (ethanoic acid), citric (2-hydroxypropane-1,2,3-tricarboxylic acid), hydrochloric and sulfuric acid

i guess its also useful for this pt:

identify data, gather and process information from secondary sources to identify examples of naturally occurring acids and bases and their chemical composition

 

[ND]

Originally posted by Hotdog
I hope they don't ask us to draw that.

Ruse trial 2002 did had a question about the ionisation of citric acid, where you deduce the which hydrogen atoms are donated. It didn't even ask you to write the equation though.

I don't remember what the question was, but most of those questions just deal with strong/weak acids and conjugates, the only thing you really need to do is recognise that citric is weak, and just use your knowledge of weak how weak acids react.

jims: i don't think either of those dotpoints requires us to draw the diagram, do you?

 

[iambored]

Originally posted by jims
yeh its in the acidic environment:

identify acids such as acetic (ethanoic acid), citric (2-hydroxypropane-1,2,3-tricarboxylic acid), hydrochloric and sulfuric acid

if it's that one you shouldn't have to draw it coz it just says identify

anway, it's not too hard to draw:
5 Cs
one C hanging off the middle bottom
3 carboxylic acid groups - on the 2 ends and hanging off C
an OH on the top of the middle C
and fill the rest with Hs

youu draw it different to me, keep it that way if u find it easier

Originally posted by ND
jims: i don't think either of those dotpoints requires us to draw the diagram, do you?

no u shouldn' thave to draw it, just identify it, but as i said it's not hard anyway

 

[parry]

its easy to draw anyway, 3 carbon chain with OH of the second one and COOH of all of them, with H's to filll in the gaps

 

[Frigid]

okay, i don't think they'd make us draw it, but recognising it from a structural diagram is possible. Citric acid is 2-hydroxypropane-1,2,3-carboxylic acid.

Look at the propane bit first. recognise it is 3 carbons in a chain:

C - C - C

At the 2nd carbon, recognise a -OH branch:

C - (OH)C - C

Noting the order of the carbons, at the 1st, 2nd and 3rd carbons, recognise carboxylic acid groups (COOH):

(COOH)C - (COOH)(OH)C - C(COOH)

There's your citric acid.

 

[xiao1985]

yea i recon...... as long as u remember the names, the structure is easy to draw...... my chem teacher repeated it like 20 million times, so each and everyone of us is like....... "okie!!! shut up already we knew it!!" =)

 

[mon_mon]

Yeah, they would never ask us to draw it, in fact, all you really need to know is that its monoprotic and a weak acid.

 

[Constip8edSkunk]

i thought it waas triprotic?

 

[inasero]

haha make sure u dont forget in the exam, so u can shift our bell curve up

 

[Constip8edSkunk]

huh?

 

[ND]

Yeh so did i.

 

[ilex_aquifolium]

I thought that it's triprotic too, doesn't it lose one hydrogen off each of the carboxcylic acid groups?

 

[toknblackguy]

we don't have to know how to do it!!
plz say we don't!

 

[Frigid]

Originally posted by toknblackguy
we don't have to know how to do it!!
plz say we don't!

its okay lah...

just remember the name and work from there. and remember that it's weak and can lose up to three hydrogen ions (triprotic).

 

[Constip8edSkunk]

Originally posted by toknblackguy
we don't have to know how to do it!!
plz say we don't!

we need to be able to identify it, possibly name it, if you can do those 2, then drawing shouldnt be much of a problem, also you need to know its acidity relative to HCl and acetic acid, ie HCl>citric>acetic in identical concentrations...