Organic Chemistry Flashcards
What is a hydrocarbon?
A hydrocarbon is carbon and hydrogen atoms only
What are alkanes?
Simplest organic compounds formed. Only contain single bonds, and are hydrocarbons
What is the simplest alkane:
Methane (CH4)
What is the homologous series?
A homologous series contains compounds:
• With the same general formula
• Have similar chemical properties i.e react the same way
• Show a gradual variation in their physical properties e.g bp increases as the carbon chain gets longer
What is the general formula of an alkane
CnH2n+2
Reaction of alkanes: Combustion:
Like all hydrocarbons, alkanes burn to give CO2 and H2O
e.g Pentane: C5H12 + 8O2 -> 5CO2 + 6H2O
If there is a poor supply of oxygen, CO and sometimes C are also formed (incomplete combustion)
What is the simplest alkene?
Ethene (C2H4)
How many covalent bonds does Carbon form?
4
What is a double bond?
Where double carbon atoms share four electrons
What does saturated mean?
All alkanes are saturated hydrocarbons. This is because it has no double bonds - it contains carbon and hydrogen only.
What does unsaturated mean?
All alkenes are unsaturated hydrocarbons. This means that they have double bonds.
Describe the reaction of alkenes with bromine, Br2:
Alkenes react with pure liquid bromine Br2 (l) or a solution of bromine water Br2 (aq). In both cases, the orange bromine water is immediately discolourised. Alkanes do not react with bromine water, unlike in alkenes, for which the bromine becomes colourless.
What is the symbol equation for reaction of an alkene and bromine?
C2H4 + Br2 -> C2H4Br2
What type of reaction is bromine water and an alkene?
Addition reaction
Describe the reaction of alkenes with hydrogenation
- Requires a catalyst of finely divided nickel
- Vegetable oils are organic compounds which contain C=C double bonds (they are usually polyunsaturated, but some are monosaturated)
- Removing some of the double bonds helps the molecules to pack together better and the liquid becomes a solid fat.
- It is used to make margarine or as an alternative to animal fats in the food industry
- If all the double bonds are removed, a saturated fat has been made which is less healthy
Symbol reaction of hydrogenation:
C2H4 + H2 -> C2H6
Why is the nickel catalyst finely divided?
To give maximum surface area