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March 28, 2024, 08:25:56 pm

Author Topic: VCE Chemistry Question Thread  (Read 2312989 times)  Share 

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thushan

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Re: VCE Chemistry Question Thread
« Reply #795 on: April 29, 2014, 08:01:51 pm »
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Do we need to know/state the state of phosphoric acid catalyst in hydration or the state of H2SO4 or any catalysts really in organic chemical pathways.

Not usually - you should know that the H2SO4 used as a catalyst in esterification must be H2SO4 (l) though - NOT H2SO4 (aq).
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Snorlax

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Re: VCE Chemistry Question Thread
« Reply #796 on: April 29, 2014, 11:42:30 pm »
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Question about naming amines
CH3CH2CH2NH2
It's okay to call this: Amino propane OR propan-1-amine? Just not 1-propyl-amine?
Is there a preferred way?

Thanks
« Last Edit: April 29, 2014, 11:44:04 pm by Snorlax »
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Re: VCE Chemistry Question Thread
« Reply #797 on: April 30, 2014, 09:18:34 am »
+1
Question about naming amines
CH3CH2CH2NH2
It's okay to call this: Amino propane OR propan-1-amine? Just not 1-propyl-amine?
Is there a preferred way?

Thanks

I've always called in propan-1-amine, but that's just me.
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Alwin

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Re: VCE Chemistry Question Thread
« Reply #798 on: April 30, 2014, 02:20:04 pm »
+1
Question about naming amines
CH3CH2CH2NH2
It's okay to call this: Amino propane OR propan-1-amine? Just not 1-propyl-amine?
Is there a preferred way?

Thanks

Amino propane (iirc) is wrong because it could refer to CH3CH2CH2NH2 OR CH3CH(NH2)CH3

You should actually call it 1-aminopropane :) (see below)
« Last Edit: May 01, 2014, 09:03:02 pm by Alwin »
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thushan

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Re: VCE Chemistry Question Thread
« Reply #799 on: April 30, 2014, 02:49:13 pm »
+2
Amino propane (iirc) is wrong because it could refer to CH3CH2CH2NH2 OR CH3CH(NH2)CH3

You should actually call it 1-aminopropane :)

propan-1-amine. 1-aminopropane is incorrect and is the old name, and those names were penalised in the 2008-2009 VCAA exam.
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soNasty

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Re: VCE Chemistry Question Thread
« Reply #800 on: April 30, 2014, 05:11:50 pm »
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how would i make salicylic acid (2-hydroxybenzoic acid) from benzene?
Also, why is this called 2-hydroxybenzene phenol, why not "1-" ?

lzxnl

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Re: VCE Chemistry Question Thread
« Reply #801 on: May 01, 2014, 07:12:53 pm »
+1
how would i make salicylic acid (2-hydroxybenzoic acid) from benzene?
Also, why is this called 2-hydroxybenzene phenol, why not "1-" ?

Erm...it's just called hydroxybenzene. There shouldn't be a number at all.

Making salicylic acid is out of the course
As for making salicylic acid, you need phenol. Look up on Wiki how to make phenol. You can use N2O and form phenol and nitrogen gas, which is probably the best path (chlorobenzene is problematic as it's not easy to just make monosubstituted chlorobenzene by itself). React with sodium hydroxide to form sodium phenolate (conjugate base of phenol). Then react with CO2 at 100 atm and 390 K to make salicylic acid.
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thushan

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Re: VCE Chemistry Question Thread
« Reply #802 on: May 01, 2014, 08:46:28 pm »
+1
how would i make salicylic acid (2-hydroxybenzoic acid) from benzene?
Also, why is this called 2-hydroxybenzene phenol, why not "1-" ?

Hey man - it's quite unlikely that you'll be expected to know how to synthesise salicylic acid from benzene in the exam. :)
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Alwin

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Re: VCE Chemistry Question Thread
« Reply #803 on: May 01, 2014, 09:01:53 pm »
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propan-1-amine. 1-aminopropane is incorrect and is the old name, and those names were penalised in the 2008-2009 VCAA exam.
Cheers for the clarification!

Hey man - it's quite unlikely that you'll be expected to know how to synthesise salicylic acid from benzene in the exam. :)
I thought that naming aromatic compounds was not in the study design ever period. (?)

@thush I think I've been out of the system too long for chemistry as you can tell by my replies :P
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Re: VCE Chemistry Question Thread
« Reply #804 on: May 01, 2014, 10:08:25 pm »
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thanks to both of you :)

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Re: VCE Chemistry Question Thread
« Reply #805 on: May 01, 2014, 10:09:45 pm »
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@thush I think I've been out of the system too long for chemistry as you can tell by my replies :P

Your nomenclature usage was penalised in 2008 apparently xP
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Re: VCE Chemistry Question Thread
« Reply #806 on: May 02, 2014, 07:01:34 pm »
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Why do non polar molecules dissolve in non polar solvents and why do polar molecules dissolve in polar solvents.
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Rishi97

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Re: VCE Chemistry Question Thread
« Reply #807 on: May 02, 2014, 07:07:35 pm »
+1
Why do non polar molecules dissolve in non polar solvents and why do polar molecules dissolve in polar solvents.

Like dissolves like.
If a molecule is polar (has an OH- group) it will be able to form hydrogen bonds with the polar substance which is water.
If a molecule is non-polar, it forms dispersion forces with the non-polar solvent
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lzxnl

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Re: VCE Chemistry Question Thread
« Reply #808 on: May 02, 2014, 08:43:20 pm »
+1
Like dissolves like.
If a molecule is polar (has an OH- group) it will be able to form hydrogen bonds with the polar substance which is water.
If a molecule is non-polar, it forms dispersion forces with the non-polar solvent

Search the chem forum for my post on this. Polar molecules also form dispersion forces with polar solvents too; it's not just the fact that the non-polar molecules form dispersion forces that is relevant.
Polar molecules don't have to contain hydroxyl groups. Formaldehyde doesn't have a OH or NH but it still dissolves really well in water (400 g/L according to Wiki). Similarly, you can dissolve as much HCl as you want in water.
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Re: VCE Chemistry Question Thread
« Reply #809 on: May 02, 2014, 09:52:38 pm »
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Search the chem forum for my post on this. Polar molecules also form dispersion forces with polar solvents too; it's not just the fact that the non-polar molecules form dispersion forces that is relevant.
Polar molecules don't have to contain hydroxyl groups. Formaldehyde doesn't have a OH or NH but it still dissolves really well in water (400 g/L according to Wiki). Similarly, you can dissolve as much HCl as you want in water.

oh ok...thanks for the clarification :)
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