Preparing For Chemistry 5070 P1 / P2

[UziB]

I'm pretty sure everyone knows about combustion

 

[multixamza01]

We can prepare Alkanes by reacting Alkenes with Hydrogen (Hydrogenation of Alkenes) .
In this reaction , Nickel is used as catalyst at 200 degree temperature .

Now we move onto Alkenes .

 

[multixamza01]

In the substitution reactions of Alkane, they undergo reactions with Group VII halogens, i.e fluorination, chlorination, bromination, iodination, and astatination reactions.

and ultraviolet light is required for the reaction to occur as the reaction is photochemical , and the reaction does not stop at any point but proceeds further and a mixture of products are formed

 

[UziB]

We can prepare Alkanes by reacting Alkenes with Hydrogen (Hydrogenation of Alkenes) .
In this reaction , Nickel is used as catalyst at 200 degree temperature .

Now we move onto Alkenes .

Alkenes have the general formula CnH2n, they are unsaturated hydrocarbons i.e have C=C bonds. They undergo the following reactions:
1) Combustion 2) Addition of Hydrogen 3) Addition of Steam 4) Addition of Haloacid 5) Addition of Halogen
They also undergo thermal decomposition in which Alkenes are broken down to form an Alkane and a smaller Alkene. The conditions for this decomposition reaction is a temperature range of 300-800 degree Celsius and using Silicon Dioxide as a catalyst.

 

[multixamza01]

Alkenes are unsaturated hydrocarbon compounds , having carbon to carbon double bonds .They have the ability to decolourise aqueous bromine . They undergo 4 types of reactions :
Combustion
Addition

They can be used to prepare Alcohols . In this reaction an alkene is reacted with steam . The catalyst is Phosphoric Acid , which acts as a hydrating agent . Temperature : 300 degree , Pressure : 70 atm .

Another reaction is one we have already done ( hydrogenation of alkenes which produces an alkane)

 

[multixamza01]

Methods to prepare Alkenes :

1. Cracking of Alkanes

2. Dehydration of Alcohols . In this reaction an alcohol is passed through concentrated sulfuric acid , and water vapors are absorbed by the acid . This is the reverse process of the earlier discussed , Hydration Reaction with Steam . A temperature of 170 degrees is required . Obviously , the products are an alkene and steam .

 

[UziB]

Sorry, in thermal decomposition an ALKANE is broken down and not an ALKENE, the alkene is formed

In the addition of Haloacid for Alkenes, they react with an acid containing a halogen. The conditions for this reaction is a catalyst i.e Aluminium Chloride. The product formed is known as a HaloAlkane.

 

[multixamza01]

Sorry, in thermal decomposition an ALKANE is broken down and not an ALKENE, the alkene is formed

In the addition of Haloacid for Alkenes, they react with an acid containing a halogen. The conditions for this reaction is a catalyst i.e Aluminium Chloride. The product formed is known as a HaloAlkane.

yeah i guess that's what is called ''cracking'' . We can also use porcelain as a catalyst , as is often seen in past paper questions

 

[multixamza01]

Moving on!

Alcohols (The Harram Part of Organic Chemistry )
someone please explain .

 

[UziB]

yeah i guess that's what is called ''cracking'' . We can also use porcelain as a catalyst , as is often seen in past paper questions

Yes it is also known as cracking actually I was correcting myself because I had stated earlier that alkenes are broken down in cracking when instead alkanes are really broken down, my mistake. And correct we can also use heated porcelain pieces as the catalyst.

 

[UziB]

Alcohols undergo 3 reactions i.e 1) Combustion 2) Oxidation and 3) Esterification.

In the oxidation of alcohols, they are heated in the presence of acidic conditions or an oxidizing agent for e.g KMnO4 to produce an alkanoic acid.

 

[UziB]

Esterification : It is a reaction in which alcohols are reacted with alkanoic acids in the presence of H+ ions (any acidic medium) to produce a sweet smelling substance known as an ester and water.

 

[scouserlfc]

Now for carboxhylic acids these another homologous series of compounds which have a -COOH functional group attached to them and the general formula is CnH2n+1COOH (where n begins from 0 and i know some may know a different formula where n begins from 1 ! ) they are acidic compounds which are weak in nature and pH varies between 4-6 mostly,they can do all reactions an acid does but with a slow rate of reaction.These compounds also combine with alcohols to form esters in the presence of conc. H2SO4 . Also like others they undergo combustion !
I guess thats all for Organic chemistry now we can proceed with Air and Atmosphere !

 

[Vogue]

79% Nitrogen
20% oxygen.
pollutants which r not normally present: oxides of Nitrogen and sulphur.
Methane and CO2 are greenhouse gases that cause global warming. global warming melts polar ice caps.
Car exhausts and poisonous fumes from industries add to atmospheric pollution.

 

[AnGeL.Of.DaRkNeSs]

i guess we dont need the ethanol preperation or ethene and methane properties like formation and reactions e.t.c in organic???

 

[Rimsa]

79% Nitrogen
20% oxygen.
pollutants which r not normally present: oxides of Nitrogen and sulphur.
Methane and CO2 are greenhouse gases that cause global warming. global warming melts polar ice caps.
Car exhausts and poisonous fumes from industries add to atmospheric pollution.

22% oxygen. one of the papers of 2011 winter had that question

 

[Fallen316]

22% oxygen. one of the papers of 2011 winter had that question

and its answer in the mark scheme was 20%

 

[Rimsa]

and its answer in the mark scheme was 20%

i dunt think so. do you remember which paper it was?

 

[Fallen316]

i dutn think so. do you remember which paper it was?

A2 a) i)
http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20O%20Level/Chemistry%20(5070)/5070_w11_qp_22.pdfhttp://www.xtremepapers.com/papers/...l O Level/Chemistry (5070)/5070_w11_ms_22.pdf

 

[Rimsa]

A2 a) i)

http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20O%20Level/Chemistry%20(5070)/5070_w11_qp_22.pdfhttp://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_w11_ms_22.pdf

oopps. kewl. my bad. someone had corrected this on my book :x
thanks
sorry Vogue