Alkanes Key Terms

These key term question cards will help you with your understanding of the basics of alkanes, the complete and incomplete combustion of alkanes and their properties. 

?
  • Created by: Molly
  • Created on: 27-04-13 16:32
What is the general formula of an alkene?
CnH2n+2
1 of 23
Why are alkanes hydrocarbons?
Because they contain ONLY carbon and hydrogen.
2 of 23
Why are alkanes described as being saturated?
Because every carbon in an alkane has four single bonds with other atoms, and it is impossible for carbons to make more than four bonds.
3 of 23
What is the general molecular shape of an alkane molecule?
Tetrahedral
4 of 23
What is the general bond angle for an alkane and why?
109.5 because they are tetrahedral.
5 of 23
Smaller alkanes are ..... at room temperature?
gases
6 of 23
Larger alkanes are ..... at room temperature?
liquids
7 of 23
Explain the boiling points of alkanes?
Alkanes have covalent bonds between molecules. Between the molecules there are van der Waals forces. The longer the carbon chain the more van der Waals because theres more molecular surface area and more electrons to interact.
8 of 23
The larger the alkane, the ....... the boiling/melting point.
higher
9 of 23
Branched chain alkanes have a ....... boiling/melting point that straight chain alkanes because?
Lower, they cannot pack together as closely and so have smaller molecular surface areas and thus less van der Waals forces.
10 of 23
If you burn an alkane completely in oxygen this is called..
Complete combustion.
11 of 23
What are the products of complete combustion?
CO2 and H2O.
12 of 23
Combustion happens between ........ so liquid alkanes have to be...... first. Smaller alkanes turn in to gases easier and so burn easier.
gases, vapourised.
13 of 23
How do you balance a complete combustion reaction involving an alkene?
Look at the number of Carbons in the alkane chain and use this for the CO2 molecule then use the number of hydrogens in the alkane to determine the number of H2O molecules.
14 of 23
Why do larger alkanes release more energy when they react? And why does this make them useful?
They have more bonds to react. This means they give out more energy and so are useful as fuels.
15 of 23
What is propane used for?
central heating and as a cooking fuel.
16 of 23
What is butane used for?
Camping gas.
17 of 23
What happens if an alkane is burnt with a limited supply of oxygen?
Incomplete combustion occurs.
18 of 23
What are the products of incomplete combustion?
Carbon monoxide and water.
19 of 23
How do you balance the equation of an incomplete combustion?
Use the number of carbons in the alkane to determine the number of carbons in the carbon monoxide. Use the number of hydrogens in the alkane chain to determine the number of water molecules.
20 of 23
What is the issue with carbon monoxide?
It is poisonous.
21 of 23
Why is carbon monoxide poisonous?
Because it is better at bonding with the haemoglobin in your blood than oxygen and so starves your body of oxygen. As a result you suffer from fatigue, nausea and headahces.
22 of 23
What needs to happen to all alkane based fuels?
They need to be properly ventilated.
23 of 23

Other cards in this set

Card 2

Front

Why are alkanes hydrocarbons?

Back

Because they contain ONLY carbon and hydrogen.

Card 3

Front

Why are alkanes described as being saturated?

Back

Preview of the front of card 3

Card 4

Front

What is the general molecular shape of an alkane molecule?

Back

Preview of the front of card 4

Card 5

Front

What is the general bond angle for an alkane and why?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all Functional Groups resources »