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Syllabus of Organic Chemistry Questions
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25-05-2013 4:23pm#1
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1. Physical properties of aromatic hydrocarbons.
Contain a benzene ring in their structure,insoluble in water, they are organic solvents (such as cyclohexane)
2. Composition of petrol.
Mostly hydrocarbons of c5-c10 (over 100 different compounds its hard to remember them all xD )
3. Hydrogen: manufacture by steam reforming of natural gas.
Isn't this dehydrocyclisation? Cyclic alkanes are converted to aromatic compounds and produces a h2
4. Solubility of ethanal in cyclohexane and water.
5. Sigma and pi bonding in benzene.
Overlap of py orbitals, which is extremely stable. ( identical c-h and c-c single bonds)
6. Aromatic compounds form the basis of dyestuffs, detergents, herbicides and many pharmaceutical compounds (one example in each case; structures not required).
All I can think of is benzaldehyde which is almond oil
9. An indication of the range and scope of the petrochemical industry (two examples of synthetic products of this industry; structures not required)
Plastics/fibers and medicines from Naphta and lubricating oil for engines
12. Reactions of carboxylic acids with magnesium, with sodium hydroxide and with sodium carbonate.
If i remember correctly Recognised as an acid if releases co2 (i will upload pic of equations in a min)
13. Example of organic synthesis: PVC from ethene (structures and synthetic route
(Uploading pic)
14. An indication of the range and scope of organic natural product chemistry (two examples of useful organic natural products)
I Just know these off the top of my head pretty sure they are right though will make sure when I get home from evening study
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3. Hydrogen: manufacture by steam reforming of natural gas.
Isn't this dehydrocyclisation? Cyclic alkanes are converted to aromatic compounds and produces a h2
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I managed to find this at the back of the chapter. What actually happens is that methane is reacted with steam, forming hydrogen and carbon monoxide
( CH4 + H20 ----> CO + H2 ).
Then Carbon monoxide is reacted with steam again and oxidises to Carbon Dioxide, forming more Hydrogen
( CO + H20 ----> CO2 + H2 ).
And thus 70% of methane is converted to Hydrogen
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are u sure they are rarely asked before? .. i seem to recall coming across all most all those points in exam papers except a few. Ok here's my attempt to answer all of those.
1. In my book it says the only aromatic hydrocarbons you need to know is benzene methy/ethyl benzene. Aromatic hydrocarbons have pleasant smells (well the early ones discovered had pleasant smells anyway), unreactive due to delocalised electrons, benzene itself is highly toxic and carcinogenic, liquid at room temperature. Insoluble in water ( non-polar) which obviously implies that its soluble in organic solvents like cyclohexane. They themselves are good organic solvents. (ok i mentioned a few chemical properties there too but nvm those)
2. Petrol is not made off any one single hydrocarbon but a mixture of a lot of different ones. typically petrol contains c5-c10 chain hydrocarbons.
3. manufacture of h2 by steam reforming of methane follows this equation CH4 + H2O
> 3H2 + CO this is done in the presence of a suitable catalyst. another method to form h2 would be by the electrolysis of water.
4. This is just like code for talking about solubility of aldehydes in cyclohexane and water. They have a polar part so the lower members readily dissolve in water(note they from hydrogen bond with water). All members readily dissolve in organic solvents. The solubility decreases with the length of the carbon chain increasing. So for ethanal it readily dissolves in water ( i think it is completely miscible with both but not sure about this )
5. ok tough one...i dont really understand this but it goes something as follows. out of the 4 electrons in C's outer shell. 3 of them from sigma bonds with the 2 C atoms on each side and the H atom. The remaining one is in the P-orbital...each p orbital overlaps sideways with its neighbouring ones to from a pi bond and you get 2 doughnut shaped electron clouds above and below the plane of the ring ( dont get this part at all i just cant visualize it) The 6 electrons are in these electron clouds somewhere and thus they are delocalised.
6. umm do u really need to know one example from each?>.> they probably would just ask you Give 2 examples etc. of what aromatic compounds form the basis off. And you have the answer to that written there. i just learned off that its forms the basis of asprin,cocaine, vanilla. These are the others from my textbook. DDT = an insecticide, Detergent = sodium dodecylbenzenesulfonate (what the hell lol), dyes = chrysoidine. seriously i doubt they would ask u anything of these.
7.no clue about this but i do know that ethene reacting with chlorine is part of the organic synthesis to from pvc. ethene reactive with water obviously froms ethanol. Others i have no idea of the importance of their products.. but once again i doubt we would be required to know these apart from ethene reacting with chlorine as part of pvc synthesis.
8. As already mentioned benzene doesn't have a fixed 3 double bonds between the carbon atoms. The 6 electrons are delocalised so this gives it extra stability and explains its unreactivity. To think of it another way the double bonds are constantly moving so theres is no fixed double bond between 2 carbon atoms ( hence the correct way to draw benzene is a hexagon with a circle in it).
9. Ummm basically everything is manufactured from crude oil. The things that jump to my mind are plastics, bitumen, but i suppose u could say any almost any organic compound.
10. i guess what it says on the tin...reduction of carbonyl compounds using h2/ni catalyst. basically just the opposite to oxidation experiment.. ethanoic acid
> ethanal
> ethanol.
11.what is the question here?. Almost all organic compounds burn to from CO2 and water. ( CO and C if not enough oyxgen). the only exception are fully halogenated alkanes. They only thing i could find in my textbook was they are added to fabrics to reduce their tendency to catch fire....one example would be CBrCF2 but once again i doubt that they would ask us something like this.
12.There is mandatory expt on this. It shows the ability of carboxylic acids to act like acids.(theres a long explanation on why they act as acids...basically its due to the inductive effect and due to the stability of the carboxylate ion)Reaction of ethanoic acid with all of the stuff u mentioned. Basically for the equation for this type of reaction is as follows.
They are acting as acids which are proton donors. So it loses one H atom and thats replaced with the metal to form a new compound and they the reaction also forms water or whatever is remaining.
So for ethanoic acid: 1. CH3COOH + NaOH
> CH3COONa + H2O (again the H is replaced with a metal ...its typical of of all acid-base reactions to form a salt and water).............................................................................^ is sodium ethanoate btw. (kindof like naming esters ...instead of a methy/ethyl group its a metal)
2. 2CH3COOH + Na2CO3
> 2CH3COONa +CO2 + H2O
3. 2CH3COOH + Mg
> (CH3COO)2Mg + H2 ( this one is just learning it off i guess)
13. Organic synthesis of PVC should be learned off as it is specifically mentioned on the syllabus. Its basically as follows:
React Ethene with Chlorine to form 1,2-dichloroethane( substitution reaction). then 1,2-dichloroethane is subject to thermal cracking which removes HCL ( elmination reaction i think - ....im pretty sure we dont need to any other elimination reaction other than removal of water from an alcohol to from an alkene) to form chloroethene which is then polymerised to from PVC ( polyvinl chloride) or poly(chloroethene). So yeah thats about it.
in equ form:.............................1,2-dichloroethane.......-HCL...........chloroethene...........Polymerisation
C2H4+ Cl2
> C2H4Cl2
> C2H3Cl
> PVC
14. Umm Oils eg clove oil and lots of pharmaeutical compound are orginally found in nature ( they are synthesized nowadays ofc) eg. penicillin. only 2 i could think off...but i suppose u could just keep going with the oils eg. rose oil.. etc
whew,
good revision for me. hope this helped and sorry if i made any mistakes in formulas etc... lots of things to type up 0 -
are u sure they are rarely asked before? .. i seem to recall coming across all most all those points in exam papers except a few. Ok here's my attempt to answer all of those.
1. In my book it says the only aromatic hydrocarbons you need to know is benzene methy/ethyl benzene. Aromatic hydrocarbons have pleasant smells (well the early ones discovered had pleasant smells anyway), unreactive due to delocalised electrons, benzene itself is highly toxic and carcinogenic, liquid at room temperature. Insoluble in water ( non-polar) which obviously implies that its soluble in organic solvents like cyclohexane. They themselves are good organic solvents. (ok i mentioned a few chemical properties there too but nvm those)
2. Petrol is not made off any one single hydrocarbon but a mixture of a lot of different ones. typically petrol contains c5-c10 chain hydrocarbons.
3. manufacture of h2 by steam reforming of methane follows this equation CH4 + H2O
> 3H2 + CO this is done in the presence of a suitable catalyst. another method to form h2 would be by the electrolysis of water.
4. This is just like code for talking about solubility of aldehydes in cyclohexane and water. They have a polar part so the lower members readily dissolve in water(note they from hydrogen bond with water). All members readily dissolve in organic solvents. The solubility decreases with the length of the carbon chain increasing. So for ethanal it readily dissolves in water ( i think it is completely miscible with both but not sure about this )
5. ok tough one...i dont really understand this but it goes something as follows. out of the 4 electrons in C's outer shell. 3 of them from sigma bonds with the 2 C atoms on each side and the H atom. The remaining one is in the P-orbital...each p orbital overlaps sideways with its neighbouring ones to from a pi bond and you get 2 doughnut shaped electron clouds above and below the plane of the ring ( dont get this part at all i just cant visualize it) The 6 electrons are in these electron clouds somewhere and thus they are delocalised.
6. umm do u really need to know one example from each?>.> they probably would just ask you Give 2 examples etc. of what aromatic compounds form the basis off. And you have the answer to that written there. i just learned off that its forms the basis of asprin,cocaine, vanilla. These are the others from my textbook. DDT = an insecticide, Detergent = sodium dodecylbenzenesulfonate (what the hell lol), dyes = chrysoidine. seriously i doubt they would ask u anything of these.
7.no clue about this but i do know that ethene reacting with chlorine is part of the organic synthesis to from pvc. ethene reactive with water obviously froms ethanol. Others i have no idea of the importance of their products.. but once again i doubt we would be required to know these apart from ethene reacting with chlorine as part of pvc synthesis.
8. As already mentioned benzene doesn't have a fixed 3 double bonds between the carbon atoms. The 6 electrons are delocalised so this gives it extra stability and explains its unreactivity. To think of it another way the double bonds are constantly moving so theres is no fixed double bond between 2 carbon atoms ( hence the correct way to draw benzene is a hexagon with a circle in it).
9. Ummm basically everything is manufactured from crude oil. The things that jump to my mind are plastics, bitumen, but i suppose u could say any almost any organic compound.
10. i guess what it says on the tin...reduction of carbonyl compounds using h2/ni catalyst. basically just the opposite to oxidation experiment.. ethanoic acid
> ethanal
> ethanol.
11.what is the question here?. Almost all organic compounds burn to from CO2 and water. ( CO and C if not enough oyxgen). the only exception are fully halogenated alkanes. They only thing i could find in my textbook was they are added to fabrics to reduce their tendency to catch fire....one example would be CBrCF2 but once again i doubt that they would ask us something like this.
12.There is mandatory expt on this. It shows the ability of carboxylic acids to act like acids.(theres a long explanation on why they act as acids...basically its due to the inductive effect and due to the stability of the carboxylate ion)Reaction of ethanoic acid with all of the stuff u mentioned. Basically for the equation for this type of reaction is as follows.
They are acting as acids which are proton donors. So it loses one H atom and thats replaced with the metal to form a new compound and they the reaction also forms water or whatever is remaining.
So for ethanoic acid: 1. CH3COOH + NaOH
> CH3COONa + H2O (again the H is replaced with a metal ...its typical of of all acid-base reactions to form a salt and water).............................................................................^ is sodium ethanoate btw. (kindof like naming esters ...instead of a methy/ethyl group its a metal)
2. 2CH3COOH + Na2CO3
> 2CH3COONa +CO2 + H2O
3. 2CH3COOH + Mg
> (CH3COO)2Mg + H2 ( this one is just learning it off i guess)
13. Organic synthesis of PVC should be learned off as it is specifically mentioned on the syllabus. Its basically as follows:
React Ethene with Chlorine to form 1,2-dichloroethane( substitution reaction). then 1,2-dichloroethane is subject to thermal cracking which removes HCL ( elmination reaction i think - ....im pretty sure we dont need to any other elimination reaction other than removal of water from an alcohol to from an alkene) to form chloroethene which is then polymerised to from PVC ( polyvinl chloride) or poly(chloroethene). So yeah thats about it.
in equ form:.............................1,2-dichloroethane.......-HCL...........chloroethene...........Polymerisation
C2H4+ Cl2
> C2H4Cl2
> C2H3Cl
> PVC
14. Umm Oils eg clove oil and lots of pharmaeutical compound are orginally found in nature ( they are synthesized nowadays ofc) eg. penicillin. only 2 i could think off...but i suppose u could just keep going with the oils eg. rose oil.. etc
whew, good revision for me. hope this helped and sorry if i made any mistakes in formulas etc... lots of things to type up
Well they definitely aren't the most common ones, and I knew that I'd be struggling if they came up. Thanks for your answers 0 -
whew, good revision for me. hope this helped and sorry if i made any mistakes in formulas etc... lots of things to type up
Actually, this is excellent revision; like on going through the chemistry book more carefully, I found a lot of these, which I didn't really come to learn off before - and I was getting an A in every test xD And I'm really afraid of like a bulk of them coming up at once
Hopefully this thread helps other people as well 0 -
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Okay so i have a question.
I am definitely doing q 1, 2 and 3, 4, water/acid q, equilibrim/rate q, Fuels q, and one of the options.
So, am i right in saying that i don't need to learn all them organic mechanisms and what not and no atom question. Obviously know the definitions and a bit of bonding, but I can leave the rest out can't i?
I sort of know that I can but really want to be certain. I am going for an A1 in chemistry. Got it in the last 2 mock papers i did so hopefully. But from above, there's no way i could get caught is there? 0 -
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outnumbered wrote: »Okay so i have a question.
I am definitely doing q 1, 2 and 3, 4, water/acid q, equilibrim/rate q, Fuels q, and one of the options.
So, am i right in saying that i don't need to learn all them organic mechanisms and what not and no atom question. Obviously know the definitions and a bit of bonding, but I can leave the rest out can't i?
I sort of know that I can but really want to be certain. I am going for an A1 in chemistry. Got it in the last 2 mock papers i did so hopefully. But from above, there's no way i could get caught is there?
If I were you, I'd cover q5. Don't take this as gospel but as far as I know, equilibrium doesn't have to come up as a full question and can come up as part of 10/11 a/b.0 -
Deleted User wrote: »If I were you, I'd cover q5. Don't take this as gospel but as far as I know, equilibrium doesn't have to come up as a full question and can come up as part of 10/11 a/b.
hmm possibly. To be honest, I don't think the acid base one has to either?
Anyway, may just look over it. Hate it though 0 -
outnumbered wrote: »hmm possibly. To be honest, I don't think the acid base one has to either?
Anyway, may just look over it. Hate it though
I hated it too and if this were just 4-5 weeks earlier I would recommend you do all the past q5s as you realise how they're really repetitive and they just stick in your mind. I don't know how you're fixed but if you feel you can do that then go ahead!
The acid/base is always combined with either water or sewage treatment for a full q. However they could put either chapter as a 10/11 a/b and leave the other section off completely. I just think that, for me anyway, q5 is a lot easier to grasp than the mechanisms and stuff.0 -
Deleted User wrote: »I hated it too and if this were just 4-5 weeks earlier I would recommend you do all the past q5s as you realise how they're really repetitive and they just stick in your mind. I don't know how you're fixed but if you feel you can do that then go ahead!
The acid/base is always combined with either water or sewage treatment for a full q. However they could put either chapter as a 10/11 a/b and leave the other section off completely. I just think that, for me anyway, q5 is a lot easier to grasp than the mechanisms and stuff.
hmm yeah maybe! I was just looking through all the papers and pre papers and i can always do 9 questions without the q5 or specific organic q. But may go over it to be safe I'll see how I'm fixed for time. Today and tomorrow are my last days on chem/spanish/accounting. Just focusing on my others now
Hopefully chemistry is a nice paper. Then again, it always is if you know your stuff haha.0 -
outnumbered wrote: »hmm yeah maybe! I was just looking through all the papers and pre papers and i can always do 9 questions without the q5 or specific organic q. But may go over it to be safe I'll see how I'm fixed for time. Today and tomorrow are my last days on chem/spanish/accounting. Just focusing on my others now
Hopefully chemistry is a nice paper. Then again, it always is if you know your stuff haha.
Yeah I know that you can leave them out but that is provided that acids/bases/water and equilibrium get their own q and you know everything else. At least we know what q5 is on before we sit the paper. I love Chemistry, it's my favourite subject 0 -
Deleted User wrote: »Yeah I know that you can leave them out but that is provided that acids/bases/water and equilibrium get their own q and you know everything else. At least we know what q5 is on before we sit the paper. I love Chemistry, it's my favourite subject
Good point. My teacher advises to stay away though as it's the worst answered question on the paper.
I like it too. The teacher is absolutely excellent! we don't even use a book! We know everything thoroughly (bar the organic/atom) haha. I'm hoping for an A1 but it's no joke...0 -
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Deleted User wrote: »I'm hoping for an A1 too and I got an A2 in the Pre :P I would say it is the worst answer on the paper but I would say it's because it's the question that people would recognise and guess even though they don't have a clue :pac:
cool well done. I got a B1 in the first mock and an A1 in the second.
Yeah that't probably it alright! 0
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