organic chem (pg 45)

Question 1

definition of a homologous series

Answer 1

a family of organic molecules with members that:
-share the same general formula
-have the same functional group
-similar chemical properties
-differ from the next by a CH2 group
-have physical properties that show gradual change as size of molecules increases

Question 2

definition of hydrocarbons

Answer 2

compounds that consists of carbon and hydrogen only

Question 3

general formula of Alkanes

Answer 3

CnH2n+2

Question 4

general formula for Alkenes

Answer 4

CnH2n (n ≥ 2)

Question 5

functional group of Alkanes

Answer 5

• no functional group
• all Alkanes have carbon - carbon bonds and all their other bonds are single

Question 6

functional group for Alkenes

Answer 6

• all Alkenes have carbon-carbon double bonds ( C=C )

Question 7

reactivity of Alkanes

Answer 7

Alkanes are saturated, therefore it is unreactive.

Their C-C and C-H are strong bonds.

Question 8

reactivity of Alkenes

Answer 8

• Alkenes are unsaturated, making them more reactive

-Alkenes undergo additional reaction

-Double bonds in Alkenes break easily to allow other atoms to add on to the carbon atoms.

Question 9

Complete combustion of Alkanes and Alkenes

Answer 9

It produces CO2 and H2O

Question 10

Incomplete combustion of Alkanes and Alkenes

Answer 10

It produces CO2, H20, soot and CO

Question 11

Why are Alkanes considered better fuels?

Answer 11

• They produce a lot of heat when burnt

-They produce less soot compared to Alkenes

Question 12

What are Polyunsaturated food?

Answer 12

Food molecules that contain many C=C bonds

Question 13

general formula of Alcohols

Answer 13

CnH(2n+1)OH

Question 14

general formula of Carboxylic acids

Answer 14

CnH(2n+1)COOH

Question 15

functional group of alcohols

Answer 15

-OH

Question 16

functional group of Carboxylic acids

Answer 16

-COOH

Question 17

chemical reactions in Alcohols?

Answer 17

Combustion and Oxidation

Question 18

Combustion in Alcohols

Answer 18

• burns cleanly with pale blue flame
• produces only CO2 and H2O
  eg C2H5OH + 3O2 —> 2CO2 + 3H2O

Question 19

Oxidation in Alcohols

Answer 19

Ethanol is oxidised to ethanoic acid by:
- oxygen in the air
- warming with acidified potassium maganate(VII) [Kmn04] which turns purple to colourless

Question 20

Physical properties of Carboxylic acids

Answer 20

turns blue litmus paper red

Question 21

Chemical reactions in Carboxylic acids

Answer 21

Reacts slowly with:

• Metals above hydrogen in RS to form organic salt & H2
• Metal carbonate to form organic salt, water and CO2
• Alkalis to form organic salt and water