SPM Chemistry Chapter 2 Carbon Compounds

Alkanes1. General Formula : CnH2n+2 (number of atoms, n = 1,2,3......)2. They are saturated hydrocarbons; each carbon atom is bonded to four other atoms by single covalent bonds. 3. The members of the family, ending with name “ane”.

Number of carbon atoms

(n)Name Molecular formula

CnH2n+2

Molar mass

(g mol-1)

Physical state at room

temperature

1 Methane C1H2x1+2 = CH4 16 Gas

2 Ethane C2H2x2+2 = C2H6 30 Gas

3 Propane C3H2x3+2 = C3H8 44 Gas

4 Butane C4H2x4+2 = C4H10 58 Gas

5 Pentane C5H2x5+2 = C5H12 72 Liquid

6 Hexane C6H2x6+2 = C6H14 86 Liquid

7 Heptane C7H2x7+2 = C7H16 100 Liquid

8 Octane C8H2x8+2 = C8H18 114 Liquid

9 Nonane C9H2x9+2 = C9H20 128 Liquid

10 Decane C10H2x10+2 = C10H22 142 Liquid

Consecutive members different in molar mass is 14 g mol-1

4. Structural formulae of alkanes

Name No. of isomersStructural formulae and Name

Methane

CH4

0

Ethane, C2H6

0

Propane, C3H8

0

Butane,C4H10

2

H │ H ─ C ─ H │ H

H H │ │ H ─ C ─ C ─ H │ │ H H

H H H │ │ │H ─ C ─ C ─ C ─ H │ │ │ H H H

H H H H │ │ │ │H ─ C ─ C ─ C ─ C ─ H │ │ │ │ H H H H

n-butane

Pentane,C5H12

3

2 - methyl propane

H H H │ │ │H ─ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H

H H H H H │ │ │ │ │H ─ C ─ C ─ C ─ C ─ C ─ H │ │ │ │ │ H H H H H

n-pentane

H H H H │ │ │ │H ─ C ─── C ─── C ─ C ─ H │ │ │ │ H H─C─H H H │ H

2-methyl butane

1 2 3 4

Hexane, C6H14

5

H │ H H ─ C ─ H H │ │ │H ─ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H

2,2-dimetyl propane

H H H H H H │ │ │ │ │ │H ─ C ─ C ─ C ─ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H

n-hexane H H H H H │ │ │ │ │H ─ C ─── C ─── C ─ C ─ C ─ H │ │ │ │ │ H H─C─H H H H │ H

2 - methyl pentane

H │ H H ─ C ─ H H H │ │ │ │ H ─ C ─── C ─── C ─ C ─ H │ │ │ │ H H─C─H H H │ H

2,2 - dimethyl butane

2,3 - dimethyl butane

H H H H H │ │ │ │ │H ─ C ─ C ─── C ─── C ─ C ─ H │ │ │ │ │ H H H─C─H H H │ H

3 - methyl pentane

H │ H H H ─C─H H │ │ │ │ H ─ C ─── C ─── C ─── C ─ H │ │ │ │ H H─C─H H H │ H

Physical PropertiesPhysical properties of alkanes

i. cannot conduct electrityii. less dense than wateriii. dissolve in organic solvents, insoluble in wateriv. low melting and boiling points

Conclusion: - molecule held together by weak intermolecular forces- properties of covalent compound

- gradually steady increase as the number of carbon in alkane increases

6. Steps to name branched alkanes;i. determined and named the long chains ii. determined and named the branch chain

CH3 : methylC2H5 OR CH2CH3 : ethylC3H7 OR CH2CH2CH3 : prophyl

iii. give number to the carbon atoms in long chain, which started from the nearest branchediv. The number for carbon atom which branched emerged from, must put before/infront the alkylv. Named the branched first, followed by the named of long chains

The word “ di, tri” is used if the branched chains is more than one

Chemical PropertiesPg 38

Reactivity of alkanes1. Not reactive/unreactive because saturated hydrocarbon2. Did not decolourized purple solution of acidified potassium manganate(VII)3. Did not decolourized reddish brown solution of bromin water 4. Neutral.

Combustion of alkanes1. In the presence of sufficient oxygen, alkanes burns to form carbon dioxide and water. – complete combustion

Chemical equation:

i. CH4 + O2 CO2 + H2O CH4 + 2O2 CO2 + 2H2O

ii. C2H6 + 7/2 O2 2CO2 + 3H2O

iii. C4H10 + 13/2 O2 4CO2 + 5H2O

iv. C6H14 + 19/2 O2 6CO2 + 7H2O

Answers i. CH4 + 2O2 CO2 + 2H2O

ii. C2H6 + 7 O2 2CO2 + 3H2O 2

2 x C2H6 + 2 x 7 O2 2x 2CO2 + 2x 3H2O 2

2C2H6 + 7 O2 4CO2 + 6H2O

iii. C4H10 + 13/2 O2 4CO2 + 5H2O

iv. C6H14 + 19/2 O2 6CO2 + 7H2O

C3H8

C5H12

C7H16

C8H18

C9H20

C10H22

2. If there is insufficient oxygen, carbon monoxide or carbon may be formed – incomplete combustion

i. CH4 + 3/2 O2 CO + 2H2O 2CH4 + 3 O2 2CO + 4H2O

ii. CH4 + O2 C + 2H2O

Halogenation1. The reaction is between alkane dan chlorine. 2. Takes place under sunlight/ultra violet light. 3. Carbon-hydrogen bonds broken and new carbon-halogen bonds

are formed. One or more hydrogen atoms in alkanes molecule may be subtituted by halogen. 4. Halogenation is substitution reaction.

Chlorination of methaneFirst stage;

H H │ | H ─ C ─ H +Cl-Cl → H — C — Cl + HCl │ | H H monochloromethane

Second stage;

Third stage ;

Fourth stage;

Overall equation/chemical equation CH4 + 4Cl2 CCl4 + 4HCl

HW: PG41 EP B no. 1-3

Prepared;Kamal Ariffin Bin SaaimSMKDBL

Alkenes1. General formulae : CnH2n

[ no alkene corresponding to n = 1 as CH2 is not exist]

2. Alkenes is unsaturated hydrocarbon because the presence of the double bond.3. Name of each members end with “ene”.

ethenes

H Cl │ | H ─ C ─ Cl + Cl2 → H — C — Cl + HCl │ | H H dichloromethane Cl Cl │ | H ─ C ─ Cl + Cl2 → H — C — Cl + HCl │ | H Cl trichloromethane Cl Cl │ | H ─ C ─ Cl + Cl2 → Cl — C — Cl + HCl │ | Cl Cl tetrachloromethane

Alkenes containing at least one carbon-carbon double bond

No. of carbon atom Name Molecular formulae Molar mass /

g mol-1Physical state at room

condition

1 None

2 Ethene C2H4 28 Gas

3 Propene C3H6 42 Gas

4 Butene C4H8 56 Gas

5 Pentene C5H10 70 Liquid

6 Liquid

7 Liquid

8 Liquid

9 Liquid

10 Liquid

WHEN THE NUMBER OF CARBON IN HYDROCARBON INCREASES/GREATER/HIGHER, THE SIZE OF HC MOLECULE IS BIGGER.

THUS, THE INTERMOLECULAR FORCES/Van der Waals FORCES IS STRONGER.

THUS, MORE ENERGY IS NEEDED TO OVERCOME THE FORCES.

4. Structure formula for few members of alkenesName Number of

isomer Structure formula and name

EtheneC2H4

0

H H │ │ C ═ C │ │ H H

Propene C3H6

0

H H │ │ C ═ C ─ C ─ H │ │ │ H H H

Butene,C4H8

3

H H H │ │ │ C ═ C ─ C ─ C ─ H │ │ │ │ H H H H

but -1- ene

H H │ │H ─ C ─ C ═ C ─ C ─ H │ │ │ │ H H H H

H H │ │ C ═══ C ─── C ─ H │ │ │ H H─C─H H │ H

but -2- ene

2-methyl propene

Pentene,C5H10

5

H H H │ │ │ C ═══ C ─── C ─ C ─ H │ │ │ │ H H─C─H H H │ H

2-methylbut -1- ene

H H H │ │ │H ─ C ─ C ─ C ═ C ─ C ─ H │ │ │ │ │ H H H H H

H H H H │ │ │ │ C ═ C ─ C ─ C ─ C ─ H │ │ │ │ │ H H H H H

pent -1- ene

pent -2- ene

H H H H │ │ │ │ C ═ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H

3-methyl but -1- ene

Hexene, C6H12

12

H H H │ │ │H─ C ─── C ═══ C ─C ─ H │ │ │ H H─C─H H │ H

2-methyl but -2- ene

H H H H H │ │ │ │ │ C ═ C ─ C ─ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H

H H H H │ │ │ │H ─ C ─ C ═ C ─ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H

H H H H │ │ │ │H ─ C ─ C ─ C ═ C ─ C ─ C ─ H │ │ │ │ │ │ H H H H H H

H H H H │ │ │ │ C ═══ C ─── C ─ C ─ C ─ H │ │ │ │ │ H H─C─H H H H │ H

H H H H │ │ │ │ C ═ C ─── C ─── C ─ C ─ H │ │ │ │ │ H H H─C─H H H │ H

H H H H │ │ │ │ C ═ C ─ C ─── C ─── C ─ H │ │ │ │ │ H H H H─C─H H │ H

H H H H │ │ │ │H ─ C ─── C ═══ C ─ C ─ C ─ H │ │ │ │ H H─C─H H H │ H

H H H │ │ │ H ─ C ─ C ═══ C ─── C ─ C ─ H │ │ │ │ │ H H H─C─H H H │ H

H H H │ │ │ H─C ─ C ═ C ─── C ─── C ─ H │ │ │ │ │ H H H H─C─H H │ H

H H H H H │ │ │ │ │ C ═══ C ─── C ─ C ─ C ─ H │ │ │ │ │ H H─C─H H H H │ H

H │ H H─C─H H │ │ │ C ═══ C ─── C ─── C ─ H │ │ │ │ H H─C─H H H │ H

H │ H H─C─H H │ │ │ H─ C ─── C ═══ C ─── C ─ H │ │ │ H H─C─H H │ H

H │ H H─C─H H │ │ │ C ═══ C ─── C ─── C ─ H │ │ │ │ H H H─C─H H │ H

Can you named the molecules?

Steps to name branched alkenes ; i. determined and named the long chains that has double covalent bondii. numbered the carbon atom from the nearest end to double covalent bondiii. determined and named the branch chain

CH3 : methylC2H5 or CH2CH3 : ethylC3H7 or CH2CH2CH3 : prophyl

vi. give number to branched chain vii. The number for carbon atom which branched emerged from, must put before/infront the alkylviii. The word “ di, tri” is used if the branched chains is more than one

Physical PropertiesPhysical properties of alkenes (similar to alkanes)

i. cannot conduct electrityii. less dense than wateriii. obeys “ like dissolve like”;

dissolve in organic solvents insoluble in water

v. low melting and boiling points, gradually steady increase as the number of carbon in alkene increases

Chemical Properties

Reactivity of alkenes1. Alkenes is more reactive

because the presence of double covalent bond, (unsaturated hydrocarbon)

2. Alkenes decolourized purple solution of acidified potassium

manganate(VII)3. Alkenes decolourized reddish brown solution of bromin water 4. Neutral.

Combustion of alkenes.

Addition Reaction (5.2)

The carbon-carbon double bond is converted into two single bonds

H H H H

C = C + X Y X C C Y H H H H

Alkenes Molecule Alkanes (Unsaturated) (Saturated)

1. Addition of hydrogen

Mixture of alkenes gas/vapour and hydrogen gas, is passed through platinum or nickel at 180 oC. The process is known as catalytic Hydrogenation.

Catalyst: platinum or nickel

H H H H Ni/Pt C = C + H2 H C C H 180oC H H H H

Ethene Hydrogen Ethane

Chemical equation: C2H4 + H2 C2H6

Example use of this process: Manufacture of margarine is through hydrogenation

2. Addition of halogens

The process is known as halogenation

H H H H

C = C + Br Br Br C C Br

H H H H Ethenes Bromine 1,2-dibromoethanes

(unsaturated) (saturated)

Chemical equation: C2H4 + Br2 C2H4Br2

[HW-notes book]Q1: Write a chemical equation reaction between but-1-ene with bromine water. Show the structural formula as well.

[HW-exercises book]Q2: Halogenation process is best used to differentiate between alkanes and alkenes. Explain how it can be done?

[notes: refer to SAB]

3. Addition of hydrogen halides

i. Alkenes reacts with hydrogen halide in room condition. Hydrogen halide molecules is added to double bond in alkenes, to produce halogenoalkane.

ii. When

hydrogen chloride gas is passed through into ethenes, monochloroethanes is produced.

H H H H C = C + H─Cl H C C Cl H H H H

Ethenes Hydrogen chloride Monochloroethanes

(Unsaturated) (Saturated)

Chemical equation: C2H4 + HCl → C2H5Cl

4. Addition of acidified potassium manganate(VII)

1. When alkenes is mixed with acidified potassium manganate(VII), its purple colour is decolourised.

2. This is because addition process occurred, a group of hydroxyl (--OH) is added to the molecules of alkenes to form a molecule of –diol (type of alcohol) which is saturated

and colourless.

C = C + H2O C C

OH OH

Alkenes alkanes-diol compound

(Unsaturated) (Saturated)

Example;

H H H H C = C + H2O + [O] H C C H H H OH OH

Ethene Ethane-1,2-diol (Unsaturated) (Saturated)

Q: Use propene as example.

H H H H H │H— C — C = C + H2O + [O] H C−C C H

│ │ H H H H OH OH

Propene, C3H6 Propane-1,2-diol

[O][from acidified KMnO4]

C3H6 + H2O + [O] C3H8O2

5. Steam (Hydration process)

1. Alkenes react with steam to produce equivalent alcohol at the temperature of 300 oC and in the pressure of 60 atmosphere.

2. Reactions catalyst by concentrated phosphoric acid, H 3PO4.

3. This method is one of the industrial preparation to produce alcohol.

H H H H C = C + H─OH H C C H H H H OH

Ethene Steam Ethanol C2H4 + H2O → C2H5OH @ C2H6O

Q: Use but-1-ene

C4H8 + H2O C4H9OH / C4H10O

Polymerization 5.3

Polymer : Large molecules made up from many identical repeating sub-units called monomers, which joined

together by covalent bond.

Polymerization is a process of repeated linking when a monomers are joined into chains

Reaction to form a polymer from alkene monomers is called an addition polymerisation

300 oC, 60 atmH3PO4

300 oC, 60 atmH3PO4

Homologous Series

Characteristic of Homologous Series

Kamal Ariffin Bin SaaimSMKDBLhttp://kemhawk.webs.com

Comparing properties of Alkanes and Alkenes

Similarities:

Properties Alkanes & Alkenes

Solubility in water NoSolubility in organic solvent YesConductivity NoBoiling and melting point Low

Molecular formula Each member of homologous differs from the next/successive member by a unit −CH2−

Molecular mass Each member of homologous differs from the next/successive member of 14 unit

Differences:

Properties Alkanes Alkenes

Reaction with oxygen, O2 gas It burned with less sooty yellow flame It burned with a more sooty yellow flame

Reaction with bromine, Br2 water The reddish-brown colour of bromine water remains unchanged

The reddish-brown colour of bromine water decolourised

Reaction with acidified potassium manganate(VII), KMnO4 solution

The purple colour of acidified potassium manganate(VII)solutions remained unchanged

The purple colour of acidified potassium manganate(VII)solutions was decolourised

ESSAY;

HOW TO DIFFERENTIATE THE ALKANE and ALKENE IN THE BOTTLES?Solutions: i. Procedure ii. Observations iii. Inference

[8marks]Sample answerAim: To investigate the liquid in bottle A and B

BA

Test tube A Test tube B

Dropper

Test tube

Procedure;1. The apparatus shown above is prepared.2. 2-5 cm3 bromine water is measured with measuring cylinder 5ml and poured into a test tube. 3. A few drops of liquid from bottle A is put/added with dropper into the test tube, and shake.4. Obsevation is recorded.5. The experiments is repeated by replace the liquid from bottle A with bottle B.

Observation:

Test Tube Observation Inference

Liquidin bottle A

The reddish-brown colour of bromine water remains unchanged Contains alkane

Liquidin bottle B

The reddish-brown colour of bromine water decolourised Contains alkene

Easylah!

Prepared by;Kamal Ariffin Bin SaaimSMKDBLhttp://kemhawk.webs.comALCOHOL

The Alcohol Family1. One of member of homologous series which contain carbon, hydrogen and oxygen.

2. General formula for alcohol is CnH2n+1OH. [n=1,2,3..]

3. Alcohol contains the hydroxyl group, -OH as their functional group. [notes: not hydroxide ion, OH- , alcohol not is alkaly ]

4. Alcohol is neutral compound.

5. Alcohol are named by replacing -e for alkane with –ol.

6. Structural formula and molecule for few alcohol.

n Name Mr Molekul Formula Structural formula

1 Methanol12+3+16+1= 32

CH3OH@

CH4O

H |H— C — OH | H

2 Ethanolvery important

12x2 + 5 +16 + 1 =

46

C2H5OH@

C2H6O

H H | |H— C — C — OH | | H H

3 Propan-1-ol 60 C3H7OH

H H H | | |H — C— C — C — OH | | | H H H

4 Butan-1-ol 74 C4H9OH

5 Pentan-1-ol 88 C5H11OH

6 Hexan-1-ol 102 C6H13OH

Q: Give names for this alcohol.

OH

CH3 CH2 CH CH2 CH2 CH3

Formula: C6H13OH

Name : HEXAN-3-OL

Naming Alcohol 1. Find the longest continous carbon chain containing –OH.- Number the carbon beginning at the end nearer to the – OH, write the number in front of the ending –ol. - Locate the alkyl group (branch chain), give number to the carbon and named the alkyl group. Put the number in

front of the group. CH3 : methyl

C2H5 atau CH2CH3 : ethyl C3H7 atau CH2CH2CH3 : propyl

- Complete the name for the alcohol

(ii)

OH

CH3 CH2 C CH2 CH2 CH3 | CH3

Formula: C7H15OHName : 3-methyl hexan-3-ol

(iii)

OH

CH3 CH2 CH CH CH2 CH3 | CH3

Formula : C7H15OHName : 4-methyl hexan-3-ol

(iii)

OH

CH3 CH CH CH CH2 CH2 | | | CH3 CH3 CH3

Formula : C9H19OHName : 2, 4 – dimethyl heptan-3-ol

(iv)

C2H5 OH

CH3 CH2 CH CH2 CH CH2 ─ CH3

Formula : C9H19OHName : 5-ethyl heptan-3-ol

Physical Properties1. Liquid at room temperature. (pg. 62) [ no gas]2. Simple alcohol are very soluble in water, infinite solubility. Methanol, ethanol dan propan-1-ol is miscible in all proportions (terlarut campur dengan air dalam semua kadaran). The rest of the alcohol less soluble or insoluble.

Isomerism Similar to alkenes, isomerism in alcohol results from the branching of the carbon chain and the different location of the

hydroxyl group.

You only have to know the isomerism in propanol dan butanol.

Q : Draw 2 isomers for propanol and 4 isomers for butanol, and dan named the isomers.

Propanol

Butanol

Propanol

H H H │ │ │H ─ C ─ C ─ C ─ OH │ │ │ H H H

H H H │ │ │H ─ C ─ C ─ C ─ H │ │ │ H OH H

Molecular formula: C3H7OH

Name: Propan-1-ol


Name: Propan-2-ol

Butanol


Name: Butan-1-ol


Name: Butan-2-ol

H H H H │ │ │ │H ─ C ─ C ─ C ─ C ─ OH │ │ │ │ H H H H

H H H H │ │ │ │H ─ C ─ C ─ C ─ C ─ H │ │ │ │ H H OH H

H H H │ │ │H ─ C ─── C ─── C ─ OH │ │ │ H H─C─H H │ H


Name: 2-methylpropan-1-ol

H OH H │ │ │H ─ C ─── C ─── C ─ H │ │ │ H H─C─H H │ H


Name: 2-methylpropan-2-ol

ETHANOL1. Preparation of ethanol.

i. Laboratory preparation (fermentation)ii. Industrial production (hydration process)

Making Ethanol Fermentation1. Two stages;

i. Fermentation ii. Purification

- through fractional distillation at 78 oC ( boiling point of ETHANOL)

Fermentation of Glucose1. Yeast is added to sugar or starch.

2. Anaerobic process ( takes place in the absence of oxygen).

3. Yeast releases enzymes. These enzymes break down the sugars/starch into glucose, C6H12O6.

4. Zymase slowly decomposes the glucose to form ethanol and carbon dioxide.

When the concentration of ethanol reach 15%, the yeast dies.

Q: How to produce pure alcohol?

A: Purified the ethanol through fractional distillation.

Purification of Ethanol1. Ethanol produced from the fermentation process is impure, because its mix with the glucose solution.

Q : Draw labeled diagram to carry out the purification of ethanol through fractional distillation process.

Delivery tube

Lime water

Beaker

Glucose + yeast

Conical flask

Zymase @ C2H5OH @ C2H6O C6H12O6 (aq) 2CH3CH2OH (l) + 2CO2 (g)

30 oC

Q: Why the solution/filtrate in rounded conical must heated at 78oC.

A: The boiling point of ethanol is 78 oC.

Q: Ethanol produced may still contains of some water. What should be done to be sure that ethanol is 100% pure?

A: Anhydrous calcium oxide or anhydrous calcium chloride is add/put into the ethanol.

Q: What is the function of;- thermometer- porcelain chips- Liebig condenser

A: thermometer is used to ensure that temperature is always at 78 oC.

B: Porcelain chips is used to avoid the solution jumped/ effervesence (breaking bubbles)

C: To cooled the ethanol vapour to become liquid.

Q: Named the process in Liebig condenser.

A: Condensation

Q: What is the properties of ethanol

●

○

XXXXXXXXXXXXXXX

Thermometer

Fractioning collum

Liebig condenser

Water in

Water out

Product from fermentation Porcelain

chips

Retort stand with clamp

Distillate (Ethanol)

Bunsen burner

Rounded conical

Water

Wire gauge

A: Properties;- colourless- volatile- good organic solvent- miscible with water- highly flammable- antiseptic- chemically reactive

Q: What is the uses of ethanol

A: Uses;- As a solvent in perfumes/cosmetics- As a thinner in varnish, ink- As a cleaner for compact disc.- As a fuel for transport- As a raw material for the manufacture of vinegar,- As a raw material to make industrial product such as

antiseptic and cough syrup.

Industrial production of ethanol

Ethene is mix with steam is passed through concentratedphosphoric acid (catalyst) at 300 oC (temperature) and 60 atmosphere (pressure).

Chemical Properties

1. Combustion

i. Alcohol are very flammable sustances. ii. Ethanol burns with non-smoky and blue flame and releases lot of heat. Suitable for use as fuel, described as clean fuel.

Q: Write combustion equation for hexanol

H3PO4 @ C2H4 concentrsted C2H5OH CH2 = CH2 + H2O —————→ CH3CH2OH

300 o C, 60 atm

C2H5OH + 3O2 2CO2 + 3H2O Ethanol Oxygen Carbon Water dioxide C6H13OH + 9O2 6CO2 + 7H2O hexanol Oxygen Carbon Water dioxide

2. Oxidationi. Ethanol can be oxidised into ethanoic acid by an oxidising agent.

[Ethanoic acid is a family of carboxilic acids]

Q: Show the structural formula for the equation above.

Q: Named 2 solutions are commonly used as oxidising agent.

(i) Acidified potassium manganate(VII), KMnO4 (purple to colourless / decolourised)

(ii) Acidified potassium dichromate(VI), K2Cr2O7 (orange to green)

Q: Draw a labeled diagram for the process.

Distillate (ethanoic acid)

- Colourless- Vinegar smell - Blue litmus paper turns red (acidic properties)

3. Dehydration

H H H O | | | ║ H — C — C — OH + 2[O] → H — C — C — OH + H2O | | | H H H

Heat

Ethanol + potassium dikromat(VI) + dilute sulfuric acid

Cold water

Distillate (ethanoic acid)

CH3CH2OH + 2[O] CH3COOH + H2O Etanol Ethanoic acid

ALCOHOL → ALKENE

1. Converted ethanol into ethene and a molecule of water.

2. The elimination of water results the formation of a carbon-carbon double bond.

3. Dehydration occur when a. ethanol vapours is passed over a heated catalyst such as.

i- Porous pot / porcelain chipsii- Purnice stone / aluminium oxide, Al2O3 /alumina

b. Ethanol is heated under reflux at 170 oC with excess concentrated sulphuric acid.

Q : Draw the structural molecule for the process

Q : Draw labeled diagram.

Prepared by;Kamal Ariffin Bin SaaimSMKDBLhttp://kemhawk.webs.comCARBOXILIC ACID

Heat

Glass wool soaked with ethanol

Heat

Ethene gas

Water

Porcelain chips


Test tube

Delivery tube

H H H H | | | | H — C — C — H → H — C ═ C — H + H2O | | H OH

CH3CH2OH CH2 = CH2 + H2O Ethanol Ethene

- H2O

General formula CnH2n+1COOH

One hydrogen atom is replaced with functional group – COOH

Why families known as carboxylic ‘acid’

H O | ║ H — C — C — OH | H

Formula: HCOOH

O ║ H — C — OH

Formula: CH3COOH

CARBOXYL GROUP

Carboxyl group plays a vital role to gives acidic properties to carboxilic acid families.

Molecular and Structural Formula

n Name Molecular formula Mr Structural formula

0 Methanoic acidC0H2(0)+1COOH

= HCOOH46

O ║ H — C — OH

1 Ethanoic acid

C1H2(1)+1COOH

= CH3COOH [C2H4O2]

60

H O | ║ H — C — C — OH | H

2 Propanoic acidC2H2(2)+1COOH

= C2H5COOH74

H H O | | ║H — C — C — C — OH | | H H

3 Butanoic acid

CH3COOH H+ + CH3COO-

Ethanoic acid

Hydrogen ion

Ethanoate ion

Naming carboxilic acids

Example 1:

Example 2:

C C C

O

O H

H

H

H

H

Carbon number 123

C C COOHH

H

H

H

C

Longest continuous chains: propanoic acid

HH

H

Attached alkyl group: 2-methyl

Carboxyl carbon: carbon number 1

Name: 2-methylpropanoic acid

C4H8O2 / C3H7COOH

Example 3:

CH3 C COOH

H

C2H5

Longest continuous chains: butanoic acid

Carboxyl carbon: carbon number 1

Name: 2-methylbutanoic acid

Attached alkyl group: 2-methyl

C2H5 C COOH

H

C3H7

Name: 2-ethyl pentanoic acid

Example 4:

Ethanoic AsidCan be prepared through oxidation of an ethanol.

Chemical equation:

This is carried out by refluxing ethanol with an oxidising agent such as acidified potassium dichromate(VI) or potassium manganate(VII) solution.

C3H7 C COOH

H

C2H5

Name: 2-ethyl pentanoic acid

H H │ │H — C — C — OH │ │ H H

H O │ ║H — C — C — OH │ H

+ 2[O] + H2O

K2Cr2O7 solutions + dilute H2SO4

reflux

CH3CH2OH + 2[O] CH3COOH + H2O Etanol ethanoic acid

Preparation of ethanoic acid through refluxing

Condenser is used to prevent the loss of a volatile liquid by vaporisation.

This method of retaining a volatile liquid during heating is called refluxing.

How to carry out the activity?

Physical Properties- pH less than 7- sharp or unpleasant smell- turn moist blue litmus paper to red- colourless liquid

Chemical PropertiesAcid Properties- Only hydrogen atom in the carboxyl group, [-COOH] can ionize in water to produce hydrogen ions, H+.

Tissel tube

Water out

xxxxxxxxxxxxxx

Label the diagram please

Water in

Liebig condenser

Rounded bottom flask

Retort stand

Absolute ethanol, C2H5OH + Acidified potassium dichromate(VI), K2Cr2O7 solution

Heat

Wire gauge

Ethanoic acid is a weak acid. Why? - it dissociates in water partially, most of

the molecules remain unchanged.

Reactions with metals- Dilute ethanoic acid reacts with reactive metal (Zn, Mg, Al) to produce a salt and hydrogen gas.

Reactions with bases- Dilute ethanoic acid neutralizes alkalis such as sodium hydroxide solution to give an organic salt and water.

- Black copper(II) oxide powder dissolves in dilute ethanoic acid.

Reactions with carbonates

CH3COOH CH3COO- + H+ CH3COO-

Ethanoic acid

Hydrogen ion

Ethanoate ion

2CH3COOH + Mg Mg(CH3COO)2 + H2 Ethanoic acid Magnesium ethanoate2CH3COOH + Zn Zn(CH3COO)2 + H2 Ethanoic acid Zink ethanoate6CH3COOH + 2Al 2Al(CH3COO)3 + 3H2 Ethanoic acid Aluminium ethanoate

CH3COOH + NaOH CH3COONa + H2O Ethanoic acid Sodium ethanoate

2CH3COOH + CuO Cu(CH3COO)2 + H2O Ethanoic acid Copper(II) ethanoate

- Dilute ethanoic acid reacts with metal carbonates to produce a salt, carbon dioxide and water.

Reactions with alcohols [Esterification]

Esterification:

Carboxilic acid reacts with alcohol to produce an ester and water.

Concentrated H2SO4 : catalyst

[will discuss more in next chapter]

Uses of carboxilic acid:

i. Ethanoic acid is known as acetic acids use in;- Food flavoring- Food preservatives- To make drugs, dyes, paints insectisides,

2CH3COOH + CaCO3 Ca(CH3COO)2 + CO2 + H2O Ethanoic acid Calcium ethanoate

2CH3COOH + Na2CO3 2CH3COONa + CO2 + H2O Ethanoic acid Sodium ethanoate

Concentrated H2SO4 Carboxilic acid + Alcohol ——— Ester + Water

plastics - To make esters for use as slovents

ii. Methanoic acid is used to coagulate latex.iii. Benzoic acids is used as food preservatives iv. Fatty acids used in making soapsv. Carboxilic acids use in the manufactured of polyester and polyamids (fibres) in textile

Conclusion on chemical reaction;

Carboxilic acid + reactive metal carboxylate salt + hydrogen

Carboxilic acid + base carboxylate salt + water

Carboxylate acid + metal carbonate carboxylate salt + carbon dioxide +

Water

Carboxilic acid + alcohol ester + water

1. Learning task 2.9 Summarizing pg 75 [notes book]

2. Effective Practise pg 75 1, 2, 3 [exercise book]

ESTER

General formula CnH2n+1COOCmH2m+1

R : alkyl group in carboxilic acidR’ : alkyl group in alcohol

Esterification- Carboxilic acid reacts with alcohol to produce ester and water.- The functional group of ester is carboxilate group. - Concetrated sulphuric acid is catalyst. - Carboxilic acid losses ‘OH’ and

O ║ CnH2n + 1C — OH + CmH2m+1OH (carboxilic acid) (alcohol)

O ║ CnH2n + 1C — O — CmH2m+1 + H2O (ESTER)

- Alcohol losses ‘H’ - The bond that ‘break up’ will ‘rejoin’ again

Naming Ester- Name of ester consists of two parts, the name of alcohol part is given first and followed by the acid part.

Example: i. Ethanoic acid + methanol methyl ethanoate + waterChemical equation:

CnH2n + 1 — C

O

O CmH2m+1

Break up and rejoin

Carboxilate group, -COO-

Derived from carboxilic acid

Derived from alcohol

CH3COOH + CH3OH → CH3COOCH3 + H2O

Q: Draw structural molecule of i. Methyl metanoateii. Pentyl propanoate iii. Propyl ethanoate

Solutions; i. Methyl metanoate

O ║ H — C — OH

Methanoic acid

H H | |H— C — C — OH | | H H

Ethanol

+

O H H ║ | | H — C — O — C — C — H + H2O | | H H

Ethyl metanoat Air

ii. Pentyl propanoate

Try now

Methyl methanoate

H |H— C — OH | H

O ║ H — C — OH

MethanolMethanoic acid

Break up and rejoin

From alcoholFrom carboxilic acid

O H ║ | H — C — O — C — H + H2O | H

methyl metanoate Air

How to carry out this process?[Success pg 378]

After boiling, Liebig condenser is rearranged To carry out the fractional distillation at 74oC – 78oC to collect ethyl ethanoate.

Physical properties of ethyl ethanoate- colourless- fragrant smell- insoluble in water- lese dense in water

Natural Sources- Most simple esters are found in fruits and flowers.

ex: benzyl ethanoate in Jasmine ethyl butanoate in pineapple

XXXXXXXXXXXXXXX

Tissel tubeLiebig condenser

Ethanol +ethanoic acid + concentrated sulphuric acid

Porcelain chip

Water bath

Water in

Water out

To prevent bumping and ensure smooth boiling

To cold the ethanol and ethanoic acid

Uniform heating

- Palm oil are liquid ester.- The higher and complex ester does not produce pleasant smells

Uses of ester

- to make perfume, cosmetics- to make artificial food flavoring

[Text Book: Table 2.8 pg 81] - used as organic solvents eg. ethyl ethanoate used in sunburn lotion, polish removers, glues. - to make synthetic polymers/fabrics- to make aspirin (pain reliever)

Exercise: Effective Practise pg 84 no. 1-3[Ex. Books]

Prepared by;Kamal Ariffin Bin SaaimSMKDBLhttp://kemhawk.webs.com

FATSFats and oils are chemically similar, but differ in physical states.

ETHANOLC2H5OH

ETHANOIC ACIDCH3COOH

Hydration process

Concentrated phosphoric acid, H3PO4 300 oC, 60 atmosphere

Dehydration process

ii. Concentrated sulphuric acid, H2SO4 180 oC (reflux)

Oxidation process

Acidified potassium manganate(VII)/Acidified potassium dichromate(VI)

GLUCOSEC6H12O6

Fermentation process

Yis (zymase)30 oC

ETIL ETHANOATECH3COOC2H5Esterification

process

Concentrated sulphuric acid,

H2SO4

CARBON DIOXIDE + WATERC2H5OH

Combustion process

Oxygen, O2

Oxygen, O2

Combustion process

i. Heated porcelain chips/ porous pot

ETHENEC2H4

PETROLEUM( Hydrocarbon)

Catalytic hydrogenation process

Nickel/platinum180 oC

Alumina, Al2O3

(heated)

Cracking process

HOT SPOT SPM’09

MEMORISED THE LABELED DIAGRAMS FOR EACH PROCESS. IT WILL HELP YOU A LOT.

Fats : - found in animals - solid in room temperature - butter and tallow (types of fat)

Oil : - fats from plants - liquid in room temperature

- palm oil, coconut oil, sunflower oil

- Fats and oil are mixtures of different esters. - Fats are formed from 3 molecules of long-

chain carboxylic acids called fatty acids with 1 molecules of alcohol called glycerol.

Formation of a fat molecule

H │H ― C ― OH │ H ― C ― OH │ H ― C ― OH │ H

Fatty acids- R1 , R2 , R3 contains 12 to 18 carbon atoms per molecule- R1 , R2 , R3 are three alkyl groups which may be the same or different- group: carboxilic acid

O ║OH ― C ― R1

O ║OH ― C ― R2

O ║OH ― C ― R3

Glycerol- propane-1,2,3-triol- group: alcohol

Importance of fats and oils- energy- nutrients- thermal insulation- protection to internal organ

H │H ― C ― OH │ H ― C ― OH │ H ― C ― OH │ H

O ║OH ― C ― R1

O ║OH ― C ― R2

O ║OH ― C ― R3

H O │ ║H ― C ― O ― C ― R1

│ │ O │ ║H ― C ― O ― C ― R2

│ │ O │ ║H ― C ― O ― C ― R3

│ H

+ 3H2O

+

Break up and rejoin

Break up and rejoin

Break up and rejoin

[Text book: Figure 2.34 pg. 86]

Saturated and unsaturated fats- Fat or oil molecules is affected by parent fatty

acids.- Fatty acids can be differentiated in two ways;

i. the length of the carbon chains(12 to 18 carbon atoms)

ii. saturated or unsaturated

Saturated fatty acid- All carbon atoms joined together by carbon-carbon single covalent bond.- example:

Lauric acid (12 carbon atoms)Palmitic acid (16 carbon atoms)Stearic acid (18 carbon atoms)

Unsaturated fatty acid- The carbon chain has one or more carbon-carbon double covalent bond.

Example: i. Oleic acid: monounsaturated fatty acid (one carbon-carbon double bond)- [no of C = 18, DB = 9&10]

ii. Linoleic acid: polyunsaturated fatty acid (two carbon-carbon double bond)

[no. of C = 18, DB = 9&10, 12&13]

iii. Linolenic acid: polyunsaturated fatty acid (three carbon-carbon dauble bond) [no. of C = 18, DB = 9&10, 12&13, 15&16]

Saturated Fats- Fats contain esters of glycerol and saturated fatty acids.

- Example: i. Tristearin ( glycerol + stearic acid)

ii. Tripalmitin (glycerol + palmitic acid)

Tristearin

Tripalmitin

H O │ ║H ― C ― O ― C ― (CH2)16 — CH3

│ │ O │ ║H ― C ― O ― C ― (CH2)16 — CH3

│ │ O │ ║H ― C ― O ― C ― (CH2)16 — CH3

│ H

- Animal fats have large proportions of saturated fats.

- They have high melting point and solids at room temperature.

Unsaturated Fats- Fats contain esters of glycerol and

unsaturated fatty acids.

Example:i. Triolein (glycerol + oleic acid)

H O │ ║H ― C ― O ― C ― (CH2)14 — CH3

│ │ O │ ║H ― C ― O ― C ― (CH2)14 — CH3

│ │ O │ ║H ― C ― O ― C ― (CH2)14 — CH3

│ H

- Plant or vegetable oils contain a large proportions of unsaturated fats. - They have lower melting points and are liquids at room tempoerature.

Converted unsaturated fats to saturated fats- Unsaturated fats can be converted into saturated fats by process called catalytic hydrogenation.

The hydrogenation process is carried out by bubbling hydrogen gas through hot, liquid oil in the presence of fine particles of nickel catalyst.

H O │ ║H ― C ― O ― C ― (CH2)7 — CH ═ CH — (CH2)7 — CH3

│ │ O │ ║H ― C ― O ― C ― (CH2)7 — CH ═ CH — (CH2)7 — CH3

│ │ O │ ║H ― C ― O ― C ― (CH2)7 — CH ═ CH — (CH2)7 — CH3

│ H

Effect of fats on health- Saturated fats (animal oil) will raise the level of cholesterol.- Cholesterol causes fatty deposites or the wall of veins or arteries.- Blood circulation is restricted and will raise the blood presure - Arteriosclerosis, can result in heart attack.- Unsaturated fats (plant oil) do not contain cholesterol. Do not cause cardiovascular problems.

Uses of palm oil- Has many advantages. - A cheaper, better and healthier oil.

[Text book: Figure 2.36 pg. 90]

Prepared by;Kamal Ariffin Bin SaaimSMKDBLhttp://kemhawk.webs.com

Natural Rubber

Natural rubber is a natural polymer.

Natural rubber is obtained from the latex secreted by rubber tree.

Latex is a colloid. It consists of rubber particles dispersed in water.

Natural rubber is poly(isopropene).

Its monomer is 2-metyhlbuta-1,3-diene or isopropene. Each isopropene molecule contains two pairs of double bonds.

The isopropene molecules undergo addition polymerization to produce a long-chain molecule called poly(isopropene)

Each rubber particles is made up of many long-chain rubber molecules, enclosed by a protein-like membrane which is negatively charged.

Polymerization of Isopropene

Negatively-charge protein membrane

Long chain rubber molecules

Rubber particle

─

─

─

─

─

─

─

─

─

─

─

─

── ─

─

──

─

──

─

─

─

─

─

──

Latex

Coagulation process of latex

H CH3 H H│ │ │ │C ═ C ― C ═ C │ │H H

+ H CH3 H H│ │ │ │C ═ C ― C ═ C │ │H H

H CH3 H H│ │ │ │C ═ C ― C ═ C │ │H H

+

H CH3 H H │ │ │ │― C − C ═ C − C ― │ │ H H

H CH3 H H │ │ │ │― C − C ═ C − C ― │ │ H H

Isoprene

H CH3 H H │ │ │ │― C − C ═ C − C ― │ │ H H

Repeated unit in polymer

polymerization

Isoprene Isoprene

Rubber particle has negatively-charged protein membrane.

The repulsion between the negatively-charged particles prevents the rubber particles from coming close to each other.

Latex could not coagulate.

Q: So what causes the latex to coagulate?

Rubber particle─

─

─

─

─

─

─

─

─

──

─

──

─

─

──

─

──

When an acid is added, the hydrogen ions, H+ neutralize the negative charges on the protein membrane.

Q: Can you named the acid that usually used to coagulated the latex in rubber industry?

A: Ethanoic acid also known as acetic acid. [notes: all acid solutions can make latex coagulate]

Q: What do you think will happen next?

─

─

─

─

─

─

─

─

─

──

─

──

─

─

──

─

──

+

+

+

++

+

+

+

+

+

+

+

+

+

++

+

+

+

+

+

The rubber particles now come close together.

This enable them to collide with one another resulting in the breakage of the protein membrane.

The rubber molecules/polymer combine with one another and entangle.

Thus, causing the latex to coagulate.

EASY lah

Q: The coagulation of latex will also occur if latex is exposed to air. Why?

A: Bacteria from air can enter latex. The growth and spread of bacteria produce lactic acid that causes the process above.

Q: Named the substance can be used to preserve latex in liquid state? Explain.

A: Ammonia, NH3. NH3 solutions contains hydroxide ions, OH- that neutralised the acid/hydrogen ions, H+ produced by the bacteria. The rubber particles remain negatively charged and the coagulation is prevented.

[notes: all alkaly solutions also can be used]

Properties of natural rubber- Soft- Elasticity decreases over time.- Easily oxidized by air. - Sensitive to heat. When heated, it becomes sticky. When cooled, it becomes hard and brittle.

Vulcanization of rubber

Properties of rubber can be improved through vulcanization.

Vulcanization is a process whereby rubber is reacted with sulphur to improved its properties.

Q: How the vulcanization process is carry out in industry?

A: 1st method: Latex is heated with sulphur, or

2nd method: Rubber products are exposed to disulphur dichloride, S2Cl2.

Q: Compare and contrast the properties of vulcanised and unvulcanised rubber.

Similarities Vulcanised and unvulcanised rubber is elastic, and heat and electrical insulator

Differences [notes: draw a table]

Properties Vulcanised rubber Unvulcanised rubber

Elasticity More elastic Less elastic

Hardness Harder Softer

Tensile strength Stronger Weaker

Resistance to heat Can withstand higher temperature

Cannot withstand temperature

Resistance to oxidation Less easily oxidized Easily oxidized

Effect of organic solvent Does not become soft and sticky easily

Become soft and sticky easily

Q: Why?

A: Improved properties of vulcanised rubber is due to the presence of cross-linkage of sulphur atoms between the rubber molecules.

Q: How the cross-linkage of sulphur atom improve elasticity and strength of the vulcanized rubber:

vulcanisation

S

S

C

C

S

S

C

C

S

S

C

C

S

S

C

C

S

S

C

CS

S

C

C

C═C C═C

C═C

C═C C═C

C═CC═C C═C

C═C

C═C

Natural rubber Vulcanised rubber

S

S

C

C

S

S

C

C

S

S

C

C

S

S

C

C

S

S

C

CS

S

C

C

Rubber molecules

Cross-linkage of sulphur atoms

A: When vulcanised rubber is streched and released, the cross linkage pull the chains back to their original arrangement.

Q: Why vulcanized rubber more resistant to heat and organic solvent?

A: The presence of sulphur cross-linkage increases the size of rubber molecules.

Q: Why vulcanized rubber more resistant to oxidation?

A: Vulcanized rubber has much lesser carbon-carbon double bond.

Uses of natural rubber

Home WorkReview Questions pg 100 - 102

i. objective (no. 1-8)ii. subjective questions (1 and 2)iii. essay (no. 1c)

SPM Question (2006)

Diagram 2 shows the stretching phases of a vulcanised rubber and an unvulcanized rubber strands.

Stretching phases Length of vulcanized rubber Length of unvulcanized rubber

Before

During

After

Diagram 2Plan an experiment to compare one characteristic shown in Diagram 2 for both types of rubber.

Your planning should include the following aspects: (a) Aim of the experiment(b) All the variables(c) Statement of the hypothesis(d) List of substances and apparatus(e) Procedure of the experiment(f ) Tabulation of data [17 marks]

Answer(i) Problem statement: Does vulcanized rubber is more elastic than unvulcanized rubber?

(a) Aim: To compare the elastic properties between vulcanized rubber and unvulcanized rubber.

(b) List of variable:

Manipulated variable = Type of rubber

Responding variable = Elasticity // length of rubber strip during and after stretching phase.

Fixed variable = Original length of rubber strip // Length/size/mass of rubber

(before stretching phase)

45 mm 45 mm

59 mm 60 mm

45 mm 50 mm

(c) Hypothesis:

Vulcanized rubber is more elastic than unvulcanized rubber. // sk3

The more elastic of the rubber, the less length of the rubber during and after stretching phase. // sk2

Rubber that is more elastic shows less length when/after it has been stretched. sk3

(iv) List of materials and apparatus: Vulcanized rubber, unvulcanized rubber, Meter ruler, 50 g weight, retort stand and clamp, clip, thread.

(vi) Procedure :1. Clip is used to hung the strip of vulcanized rubber.2. The original length of the vulcanized rubber is

measured.3. A weight of 50 g is hung on the strip of vulcanized rubber. 4. The increased in length of the vulcanized rubber

strip is measured. 5. The weight is removed. 6. The final length of the vulcanized rubber strip is measured. 7. Step 1 to 6 are repeated using unvulcanized rubber.

(vii) Tabulation:

Type of rubber strip Original length /mm

Final Length when weight is hung /mm

Increase in length /mm

Final length when weight is removed /mm


Clip

Rubber strip

Thread

Weight 50 g

Vulcanized rubber 45 59 14 45

unvulcanized rubber 45 60 15 50

HOT SPOT SPM 2008

Prepared by;

Kamal Ariffin B SaaimSMKDBL

Manipulated variable: Action to be taken:

Responding variable: Action to be taken:

How the variable responds?:

Fixed variable: Action to be taken:

Alumina, Al2O3

C9H20 (ce) ———— C2H6 (g) + C7H14 (g) PanasNonana Etana Heptena

Alumina, Al2O3

C9H20 (ce) ———— C2H6 (g) + C7H14 (g) PanasNonana Etana Heptena

SPM Chemistry Chapter 2 Carbon Compounds

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Transcript of SPM Chemistry Chapter 2 Carbon Compounds