MARKING SCHEME : CARBON COMPOUND

MARKING SCHEME : CARBON COMPOUNDActivityAnswer

11. carbon 6 saturated ; 2. organic ; inorganic 7 saturated hydrocarbon3. inorganic 8 unsaturated hydrocarbon4. Hydrogen ; carbon 9 petroleum

5. non hydrocarbon 10 carbon dioxide ; water

2a) Refer to Form 5 text book page 37 b) the relative molecular mass ; increase. Van der Waals ( intermolecular force) ; overcome c) molecules. ; freely

d) (i) 2 C2H6 (g) + 7O2 (g) ( 4CO2 (g) + 6H2O (l)

(ii) C3H8 (g) + 5O2 (g) ( 3CO2 (g) + 4H2O (l)

31 14

2 4

3 4

4 single covalent

5 methane

6 Cn H2n+2 n= 1,2,3. 7 refer to F5 textbook page 37

8 neutral

9 carbon dioxide , water

10 sooty

11 chlorine , bromine

12 - ane

4Refer to F5 textbook page 39 -41

5a) Refer to F5 textbook page 45

b) i) unsaturated ii) ene , Cn H2n n= 2,3iii) low , increases

iv) low

v) immiscible/insoluble , soluble

vi) cannot

vii) sooty , higher

viii) more , double

ix) bromine , potassium manganate(VII)

x) polymerization

6a) i) ethene v) chloroethene ii) propene vi) 2-methylpropene

(iii) but-1,3-diene vii) 1-chloropropene

(iv) 3-methylbut-1-ene viii) but-2-ene

b) refer to F5 textbook page 55-56

7Refer to F5 textbook page 49 - change ethene to propene

8a) Hexene burns with a yellow and a very sooty flame

Hexene decolorizes reddish- brown bromine

Hexene decolorizes purple acidified potassium manganate (VII)

solution

b) Hexane = 83.72 % ; Hexene = 85.71 %

Hexane can be a good fuel because the percentage of carbon is low hence

produce less soot.

c) * cannot dissolve in water * cannot conduct electricity * low melting and boiling point * neutral

* Produse CO2 and water when burnt in oxygen

d) - Alkene produce more soot - alkane produce less soot - Alkene decolorized bromine water alkane colour unchange - Alkene decolourized the purple colour of acidified KMnO4 solution -

Alkane does not change the purple colour.

9a) i) isomerisme (ii) Isomer iii) alkyl group iv) ethane and propene v) butane

b i) 3 isomers : but-1-ene ; but-2-ene ; 2-methylpropene

ii) 2 isomers : butane ; 2-methylpropane

iii) 3 isomers ; pentane ; 2-methylbutane ; 2,2-dimethylpropane

10a) i) hydroxyl / -OH v) molecular mass ii) Cn H2n+1OH n, 1,2,3,3 vi) alkeneiii) Higher ; OH/hydroxyl vii) solvents, cosmeticsiv) stronger, Viii) non hydrocarbon / carbon / organicb) i) methanol ii) ethanol iii) propan-1-ol

iv), v) vi) refer to F5 textbook page 56

c) (i) propan-1-ol ; propan-2-ol

(ii) butan-1-ol ; butan-2-ol ; 2-methylpropan-1-ol;

2-methylpropan-2-ol

11a)

Physical

properties

Description

Physical state at room temperature

First 12 alcohols are liquid at room temperature

Smell and colour

Alcohols are colourless and has a pleasant smell

Solubility in water

First three alcohols are very soluble in water

( miscible in all proportions)

Volatility

Alcohols are volatile

Boiling point

Boling point alcohols are higher than the alkanes with the same number of carbon.

As the size of molecules increases ,the boiling point of alcohols increases.

b) (i) yeast released biological enzymes, zymase. Zymase decomposes

glucose to form ethanol and carbon dioxide. (ii) Chemical equation : C6 H12 O6 (aq) ( 2CH3 CH2 OH(aq) + 2CO2 (g (iii)

Temperature : 18-20 0 C

Catalyst : yeast (zymase)

Other condition : absence of oxygen

(iv) Disadvantage : The yeast dies and the fermentation process stop when the concentration of ethanol formed reaches about 15%. Hence it is impossible to get pure ethanol

c) (i) C2 H 4 (g) + H2O (g) ( CH3CH2OH (g) (ii) temperature : 3000 C

Pressure : 60 atm

Catalyst : phosphoric acid.

12

a) 1 In excess oxygen : Carbon dioxide and water In limited oxygen : Carbon, carbon monoxide and water 2 Oxidation of ethanol : Ethanoic acid and water

Oxidation of propanol : Propanoic acid and water

3 Set of apparatus : refer to F5 practical book

b) 1.T 6 F

2 T 7 T

3.F 8 F

4 T 9 T

5 T 10 T

13

b)Methanoic acid

Ethanoic acid

Propanoic acid

Butanoic acid

2-methylbutanoic acid

Methyl propanoic acid

c) i) General formula : CnH2n + 1 COOH ii) 60 iii) ethanoic acid

14

a) hydration ; oxidationb) refer to F5 textbook page 71

c)

Observation

Inferrence

1

The metal carbonate dissolves,

Efferverscence occurs

Carbon dioxide gas released

Gas turns lime water cloudy

2

Magnesium dissolves

Bubbles of gas given off

Hydrogen gas released

Gas burns with a pop sound

3

The black powder dissolves to form a blue solution.

Blue solution shows the presence of Cu2+ ion.4

A colourless oily layer floats on the water and gives pleasant smell.

Ester is formed,

ethyl ethanoate

15a)

Formula

Name

Carboxylic acid

Alcohol

HCOOC2H5

Ethyl mathanoate

Methanoic acid

Ethanol

a) CH3 COOCH3Methyl ethanoate

Ethanoic acid

Methanol

b) CH3 COOC3H7

Propyl ethanoate

Ethanoic acid

propanol

c) C2H5 COOCH3

Methyl propanoate

Propanoic acid

Methanol

d) C3 H7COOC3H7

Propyl butanoate

Butanoic acid

propanoll

b) i) methylpropanoate (ii) ethylbutanoate

(iii) prophylethanoat

16a)

b) i) bananas (ii) oranges (iii) pineapples

17

a) i) alcohol ii) alkene iii) carboxylic acid iv) ester

b)

P Q R S

18

I) a) lipid g) triglycerides b) ester h) chloroform c) glycerol , fatty acids i) energy d) solid , liquid j) saturated, harden , stroke, High blood

e) carbon pressure, heart attack

f) ester link k) hydrogenation

l) margarineII) Comparison of fats and oils

Comparison

Oils

Fats

Source

plants

Animals

Melting point o C

< 20 / lower

> 20 / higher

Physical state at room temperature

Liquid

Solid / semi solid

Cholesterol content

low

high

Examples

Peanut oil, soybean oil

Butter , lard

Molecular structure

Contain a high percentage of unsaturated carboxylic acid

Contain a high percentage of saturated carboxylic acid

III) Similarities

In terms of

similarities

Molecular formula

The molecules contain of elements carbon, hydrogen and oxygen

Type of compound

They are naturally occurring esters

Type of bond

They are big covalent molecules.

19a)

Sterilisation - The fresh fruit bunches are sterilized is large pressure vessels at 140o C for 60-90 min. The heat from the steam kills fungus and bacteria

Stripping - The oil palm fruit is separated from the bunch

Digestion - Breaking down the oil-bearing cells. Crush the palm oil fruits

Pressing - hydraulic press is used to press out as much oil as possible

Purification - The mixture is filtered to remove solid or coarse fibre and allow to settle in an a large clarification tank. The oil is skimmed off and dried in a vacuum drier.

b) State 5 benefits of palm oil compared to other vegetable oils

i) rich in vitamin A and E

ii) stable at high temperature

iii) cholesterol free and can lower the cholesterol level

iv) easily absorbed and digested by our body

v) cheap.

20(a )

(i)-Bacteria from the air slowly attack the protein on the membrane of the

colloidal particles to produce lactic acids.

-ionisation of lactic acids produce hydrogen ions, H+

-H+ ions from the acids neutralize the negatively charged membranes of

the bcolloidal particles. Repelling forces between colloidal particles

disappear.

-collisions of these neutral particles cause their membranes to break up,

rubber polymers are set free.

-the free rubber polymers combine together to form large lumps.

(ii)

- Positively charged H+ ions from the acids neutralise the negatively

charged membranes of the colloidal particles. Repelling forces between

colloidal particles disappear.

-collisions of these neutral particles cause their membranes to break up,

rubber polymers are set free.

-The free rubber polymers combine together to form large lumps.

(iii )

-Hydroxide ions, OH- from the aqueous ammonia solution neutralise the

lactic acids produced by the bacteria in the latex.

-the negatively charged on the membrane of the colloidal particles remain.

-the repelling forces between the particles keep them apart.

-no coagulation of latex occurs

(b)

Aspect

Unvulcanised rubber

Vulcanised rubber

Structure

More C=C- bonds in rubber molecule

Less C=C bonds

Oxidation

Easily oxidised

Resist oxidation

Resistance of heat

Non-resistant

Easily melt and decomposed

More resistance

Strengh

Soft and easily changes shape

stronger

Elasticity

Less elastic

Easily stretched but difficult to return to its original shape

More elastic

Difficult to be stretched but readily returns to its original shape

211 (a) 1,2-dibromopropane

(b) (i) Propene gas and acidified potassium manganate(VII) solution

(ii) C3H6 + (O) + H2O C3H6(OH)2

(c) (i) Hydrogenation (ii) Nickel

(d) (i) A mixture propane gas (C3H8) and chlorine gas (Cl2) is exposed to

ultraviolet light.

(ii) Steamy fumes are produced.

(e) (f) (i) Polymerisation (ii) To make plastic bottles

(g) % of carbon by mass in C3H6 12(3) = 85.71%

12(3) + 1(6) % of carbon by mass in C3H8 12(3) = 81.82% 12(3) + 1(8) % of carbon by mass in C3H6 is higher than that in C3H8.

Hence, C3H6 burns with a sootier flame than C3H8.

2 (a) CnH2n + 2 ; n = 1, 2, 3, ..... (b) A : carbon-carbon double bond // - C = C

B : carboxyl group // - COOH

(c)

(d) (i) Butyl propanoate

(ii) Sweet / pleasant /fragrance / fruity smell

(e) C4H8 + 6O2 4CO2 + 4H2O

mol A = 11.2 // 0.2 56

mol CO2 = 4 x 0.2 // 0.8

No of molecule CO2 = 0.8 x 6.02 x 1023 // 4.816 x 1023

General formula

CnH2n + 1 COOH

Ethanoic acid

- colourless liquid at room

conditions.

has sharp and pungent smell.

boiling point 118o C

soluble in water

pH 3 - 4

weak acid and names end with

oic acid . Eg. ethanoic acid.

Ethanoic acid normally prepared by oxidation of an alcohol

Uses :

- food preservative ( benzoic

acid)

- food flavouring

- ethanoic acid and methanoic

acid are used to coagulate

latex in rubber industry

- making ester and soft drinks

CARBOXYLIC ACIDS

an organic acid with carboxyl

group COOH ( )

- esters are colourless liquids

- sweet and fruity smell

- volatile, insoluble

- less dense than water

uses of ester,

as food flavouring

to pleasant aromas for making perfumes

as organic solvents for glue, varnish and paint

found in flowers and fruits. The fragrance of flowers and fruits is due to the presence of esters

product of an esterification reaction between a carboxylic acid and an alcohol.

the name of an ester consists of two words. The first word originates from alcohols, the second is from the carboxylic acids. All of them end with -oate

the functional group is COO- or carboxylate group

The general formula is

CnH2n+1COOCmH2m+1

contain carbon, hydrogen and oxygen

Ester is a non-hydrocarbon organic compound

ESTERS

I

H

I

H

O

II

H - C C - OH

O

II

H C - OH

I

H

I

H

O

II

H - C C - OH

I

H

I

H

I

H

I

H

O

II

H - C - C C - OH

I

H

I

H

I

H

I

H

I

H

O

II

H - C - C - C C - OH

I

H

I

CH3

I

H

I

H

I

H

O

II

H - C - C C - OH

I

H

I

CH3

I

H

I

H

I

H

O

II

H - C - C - C C - OH

I

H

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