OCR AS Chemistry F322 Hydrocarbons Quiz

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Created by: Natasha
Created on: 09-04-12 16:55

1. What is the general fromula of an alkene?

CnH2n
CnHn
C2nHn
CnH+1

1 of 8

2. For an E/Z isomer each carbon in the C=C double bond must be bonded to two different groups.

True
False

3. In combustion, the longer the chain...

the more oxygen that will be needed
the less oxygen that will be needed

4. Why are cyclic hydrocarbons added to petrol?

To improve combustion
To lower cost of petrol
To produce less unwanted products
To reduce harmful fumes

5. In the initiation step of free radical substitution what type of fission takes place?

Homolytic
Heterolytic

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Comments

Liam Crawford

Report Tue 10th April, 2012 @ 14:32

For question 6, there are no lone pairs so there is no hydrogen bonding; there is if its an alcohol due to the OH group but alkanes have only van der Waals. as you increase the chain length you have more points of contact so the van der Waals forces increases. Also cyclic alkenes do improve combustion because they are weaker so easier to break for somplete combustion. however this also reduces the harmful fumes aka Carbon monoxide- which is produced when incomplete combustion happens often with aliphatic alkenes.

ELectrica!

Report Tue 8th May, 2012 @ 12:21

i agree, cyclic alkenes do improve combustion because they are smaller/weaker so easier to break for complete combustion