Qualification > Sciences
Chemistry P3 7/6/2010
Ivo:
--- Quote from: jellybeans on June 01, 2010, 02:28:54 pm ---how do you know what the isomers are named?
--- End quote ---
It's complicated. We shall use the isomers of butane as the example. The first one is easy, just butane. The second one:
a) You take the longest carbon cahin and name the compound after the number of carbon atoms in the longest chain. In this case, there are three carbon atoms in the longest chain. So it is named after propane.
b) You then look for the alkyl side chain. In this case it is a methyl group (CH3). So the compound is methylpropane.
c) You then have to number the alkyl group side chain by counting the numbers of the carbon atoms from one end of the carbon chain. You count from the end of the carbon chain that gives you the lowest number. In this case counting from the left/right, the alkyl group is on the second carbon atom. So the compound is 2-methylpropane.
jellybeans:
--- Quote from: Ivo on June 01, 2010, 02:47:20 pm ---It's complicated. We shall use the isomers of butane as the example. The first one is easy, just butane. The second one:
a) You take the longest carbon cahin and name the compound after the number of carbon atoms in the longest chain. In this case, there are three carbon atoms in the longest chain. So it is named after propane.
b) You then look for the alkyl side chain. In this case it is a methyl group (CH3). So the compound is methylpropane.
c) You then have to number the alkyl group side chain by counting the numbers of the carbon atoms from one end of the carbon chain. You count from the end of the carbon chain that gives you the lowest number. In this case counting from the left/right, the alkyl group is on the second carbon atom. So the compound is 2-methylpropane.
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THANK YOU ! :D
J.Darren:
Properties of Alcohols :
-OH (Hydroxyl) functional group
General formula : Cn H(2n+1) OH
Ethanol can be manufactured :
- Hydration of ethene
- Fermentation
Ethanol burns with a clean flame. It is used for camping stoves or as a fuel for cars.
The complete combustion of etanol produces carbon dioxide and water.
Ethanol is also used as a fuel, as a solvent in perfume, alcoholic drinks and making esters.
J.Darren:
Properties of Organic Acids :
-COOH functional group
General formula : Cn H(2n+1) COOH
Ethanol is oxidised to ethanoic acid.
Ethanol + O2 (from the air) -> Ethanoic acid + Water
When ethanol is heated with acidified K2Cr2O7 (Potassium dichromate), ethanoic acid is formed.
Ethanol + O2 (from the oxidising agent) -> Ethanoic acid + Water
Organic acids are weak acids, they are partially ionised in aqueous solution. They all have the typical acid properties.
Metal + Acid -> Salt + Hydrogen
Magnesium + Ethanoic acid -> Magnesium ethnoate [(Ch3COO)2Mg] + Hydrogen
Base + Acid -> Salt + Water
Magnesium + Ethanoic acid -> Magnesium ethnoate [(Ch3COO)2Mg] + Water
Carbonate + Acid -> Salt + Carbon Dioxide + Water
Sodium Carbonate + Ethanoic acid -> Sodium ethnoate [(Ch3COO)Na] + Carbon Dioxide + Water
J.Darren:
Properties of Esters :
Ethanoic acid + Ethanol -> Ethyl Ethnoate + QWater
Condition :
- Heat
- Concenterated sulphuric acid as catalyst
Esters are used in food flavourings.
When writing the name of an ester, the group from the alcohol comes before the part from the part from the acid. For example if methanol is reacted with propanoic acid, we will get methyl propanoate.
When drawing an ester, the acid part is on the left and the alcohol part is on the right.
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