Alkenes

Question 1

Alkene general formula

Answer 1

CnH2n

Question 2

What are alkenes

Answer 2

Unsaturated hydrocarbons (have at least one C=C double covalent bond)

Question 3

Why do alkenes get attacked by electrophiles

Answer 3

Two pairs of electrons in C=C bond means really high electron density- reactive

Question 4

Test for alkenes

Answer 4

• Add orange bromine water
• changes colour from orange to colourless solution if alkene
• electrophilic addition

Question 5

What reactions do alkenes undergo

Answer 5

Electrophilic addition- hydrogen halides, H2SO4, Br2

Question 6

What are major and minor products

Answer 6

• hydrogen halide adds to unsymmetrical alkene 2 products

- carbocations with more alkyl groups more stable because they push the electron density toward the carbocation

Question 7

What are polymers

Answer 7

Long chains of molecules formed when lots of small molecules (monomers) join together

Question 8

Addition polymers

Answer 8

Alkenes double bonds open up and join together to make long chains
-saturated, non polar, very unreactive

Question 9

Properties of polyalkanes

Answer 9

• non polar, chains helped by van deer waals

- the longer, straighter chains have stronger van deer waals so are strong and rigid, unlike branched chains

Question 10

How can you modify properties of polymers

Answer 10

-add a plasticiser- get between polymer chains push them apart, reduce strength intermolecular forces, slide around more, more flexible

Question 11

How to draw repeating unit of addition polymer

Answer 11

Draw the two alkene carbons, replace double bond with single bond