C6 - Organic chemistry

Question 1

How many bonds does carbon always make?

Answer 1

4 bonds

Question 2

What is a hydrocarbon?

Answer 2

A compound made of ONLY carbon and Hydrogen

Question 3

What are the two types of hydrocarbons?

Answer 3

Alkane = contains single bonds between carbon atoms
Alkene = contains at least one double bond between carbon atoms

Question 4

Alkane general formula:

Answer 4

C(n)H(2n+2)
Eg: If an alkane has 5 carbon atoms, state it’s molecular formula?
C5H((2x5)+2) = C5H12

Question 5

Alkanes in order of carbons and molecular formula?

DRAW THEIR DISPLAYED FORMULA?

Answer 5

1 carbon atom: MethAne -> CH4

2 carbon atoms: EthAne -> C2H6

3 carbon atoms: PropAne -> C3H8

4 carbon atoms: ButAne -> C4H10

5 carbon atoms: PentAne -> C5H12

-Either use general alkane formula: C(n)H(2n+2) or add CH2 from previous alkane to work these out

Question 6

What does a saturated hydrocarbon like Alkanes mean?

Answer 6

The carbon atoms are held together by single bonds

Question 7

Reactivity of alkanes?

Answer 7

They are fairly unreactive (but they do burn well) as they have single bonds between carbon atoms

Question 8

What reactions can alkanes do?

Answer 8

Substitution reactions
eg. when alkane reacts with chlorine in sunlight
DRAW MOLECULAR FORMULA OF THIS REACTION

Question 9

What is the general formula of alkenes?

Answer 9

C(n)H(2n)

Eg. If an alkene has 5 carbon atoms, state its molecular formula -> C5H10

Question 10

Alkenes in order of carbons and molecular formula?

DRAW THEIR DISPLAYED FORMULA?

Answer 10

1 carbon atom: MethEne -> CH2 (doesn’t exist as carbon cannot make 4 bonds)

2 carbon atoms: EthEne -> C2H4

3 carbon atoms: PropEne -> C3H6

4 carbon atoms: ButEne -> C4H8

5 carbon atoms: PentEne -> C5H10

-Either use general alkene formula: C(n)H(2n) or add CH2 from previous alkene to work these out

Question 11

What does an unsaturated hydrocarbon like Alkenes mean?

Answer 11

They have at least one double bond between carbon atoms

Question 12

Reactivity of alkenes?

Answer 12

They are reactive as they have at least one double bond between carbon atoms

Question 13

What reactions can alkenes do?

Answer 13

1) Complete combustion - with excess of oxygen:
The alkene reacts with oxygen to form carbon dioxide and water
EG. C2H4 + 3O2 -> 2C02 + 2H20

2) Incomplete combustion - with limited oxygen:
The alkene reacts with limited oxygen to form carbon monoxide and water
EG. C2H4 + 202 + 2CO + 2H20

3) Reaction with bromine water
DRAW DISPLAYED FORMULA EQUATION
The double bond in alkene breaks to a single bond and the bond between Br2 (B-B) breaks. The bromine atoms join the carbon atoms

4) Addition of H2
- 300 degrees and nickel catalyst
DRAW DISPLAYED FORMULA EQUATION
The double bond in alkene breaks to a single bond and the bond between H2 (H-H) breaks. The hydrogen ions join carbon atoms to form alkane.

5) Addition of H20
The double bond in alkene breaks to a single bond and the bond between H20 (H-OH) break. The H and OH ions join carbon atoms to form an alcohol.

Question 14

How to test for Alkenes?

Answer 14

Alkenes decolourise Bromine water (orange brown colour) to colourless if present.