Compounds that contain carbon element.

* Can be found in living organisms * Can be found in natural sources

Activity 1

Instruction: Put a tick ( / ) in the appropriate column

1. Classify the substances into organic and inorganic compounds.

Substance Organic compound Inorganic compoundSugarAmino acidsCarbon dioxide gasesCopper(II) carbonateLatexHydrogen cynide

Table 1

1. Organic compounds

1

CARBON COMPOUNDS

2. Inorganic compounds

2.0 CARBON COMPOUND

Simplest organic compound Only formed by carbon and hydrogen elements

# Single covalent bond # Two covalent bond (double bond)

Alkanes is a saturated hydrocarbons with single covalent bonds which consist of carbon and hydrogen only.

General formula : CnH2n+2 where n = 1, 2, 3,4, ……….

Molecular formula Number of carbon Structural formula Chemical nameCH4 1

Methane

C2H6 2Etane

C3H8 3Propane

C4H10 4Butane

2

HYDROCARBON

Saturated Unsaturated

2.1 HYDROCARBON

2.2 ALKANES

Does not dissolve with water and does not conduct electricity Molecular size increases when the number of carbon atom per molecule

increases Low boiling and melting points due to weak Van der Waals force Low density and increases gradually as the number of -CH2- groups increases

Does not react with most chemicals at room temperature Neutral in nature Complete combustion while burnt in excessive oxygen to produce carbon

dioxide, water and energy Example: C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(liq)

The combustion produces more soot with the increase of percentage of carbon in the alkanes

Subtitution reaction happens when alkanes and chlorine is exposed to sunlight or ultraviolet rays

Activity 1.2

Physical Properties of alkanes

Instruction: Put a tick ( / ) in the appropriate column

Physical Properties True False1. Physical properties of alkanes change gradually when the number of carbon atoms 2. Melting point of alkanes decrease with the increasing number of carbon atoms per molecule.3. Alkanes compound dissolve in water

4. Alkanes conduct electricity

5. Density of alkanes increase with the increasing number of carbon atoms per molecule.6. Butane, C4H10 exist in gases state at room temperature

Activity 1.2

3

A. Physical properties

B. Chemical Properties

2.21 Properties of alkanes

Physical Properties of alkanes

Instruction: Put a tick ( / ) in the appropriate column

Physical Properties True False1. Physical properties of alkanes change gradually when the number of carbon atoms 2. Melting point of alkanes decrease with the increasing number of carbon atoms per molecule.3. Alkanes compound dissolve in water4. Alkanes conduct electricity5. Density of alkanes increase with the increasing number of carbon atoms per molecule.6. Butane, C4H10 exist in gases state at room temperature

Activity 1.3

Chemical Properties of alkanes

Instruction: Write the molecule formula for the products of the reaction below.

combustion combustion

+ excess O2 + limited O2

+ Cl2 Subtitution (sunlight) reaction

4

Ethane, C2H6

2.3 ALKENES

Unsaturated hydrocarbons with two covalent bonds (doubled bond). General formula : CnH2n where n = 2, 3, 4, 5 ….

Molecular formula

Number of carbon atoms

Structural formula Chemical name

C2H4 2Ethene

C3H6 3Propene

C4H8 4Butene

C5H10 5Pentene

Almost similar to physical properties of alkanes Does not dissolve with water and does not conduct electricity Low boiling and melting points and increases gradually as the number of –CH2- groups increases Low density and increases gradually as the number of carbon atom increases

Neutral in nature Complete combustion in excessive oxygen

Example: 2C3H6(g) + 9O2(g) → 6CO2(g) + 6H2O(ce)

Combustion in air produces soot Harder to get combusted when molecular size increases gradually Reactivity increases due to its double bond

C = C + A-B C C

5

A. Physical Properties

B. Chemical Properties

2.31 Properties of alkenes

A B Alkenes Chemicals Reaction product (unsaturated) (saturated)

Example: Reaction between alkenes and halogens

Summary the reaction of alkene (ethene), C2H4

C2H6 C2H5Br + H2 + HBr CO2 and H2O + H2O C2H5OH + excess O2

+ KMnO4/H+

+ insufficient O2 C2H4(OH)2

C, CO, + Cl2 CO2 and H2O Polymerization C2H4Cl2

Activity 1.4

Instruction: Match the description with the correct term.

Description Match AnswerAn unsaturated hydrocarbon Homologous seriesA group of organic compounds related by their structure

Alkene

Addition of a molecule to the carbon, C atoms of a double bond

Addition reaction

Isomers are molecules having the same atoms with different arrangement or molecules with same molecular formula but different structural formula.

Example: H H H H H CH3 H

H – C – C – C – C – H H – C – C – C – H

H H H H H H H Butane, C4H10 metilpropana, C4H10

6

2.4 ISOMERISM

C2H4

Number of isomer increases when the number of carbon atom per molecule increases which are represented by different molecular formulae.

Naming isomers :

- IUPAC nomenclature is used to name isomers. - The names are made up of three parts as shown below.

Prefix Stem SuffixTells the side-chains

Tells the number of carbon, C atoms in the longest chain

Tells the homologous series

- Example :

2,2-dimethylpropane

Prefix Stem Suffix2,2- dimethyl- shows two methyl group bonded to second carbon, C atom

prop- Shows three carbon, C atoms in the longest chain.

ane-The homologous series is alkane

Activity 1.5

Instruction: Drawing isomers for carbon compound

Molecular formulaButane, C4H10 Butene, C4H8 Pentene, C5H12

7

2 isomers 3 isomers 5 isomers

STRUCTURAL

FORMULAE

8

ASSESSMENT

A. Objective questions:

1. A hydrocarbon is a chemical compound consisting ofA. carbon and oxygen onlyB. carbon and hydrogen onlyC. carbon, hydrogen and oxygen onlyD. carbon, hydrogen, oxygen and nitrogen only

2. Which of the following are isomers of butane? I

II

III

IV

A. I and III onlyB. II and IV onlyC. I, II and III onlyD. I, II, III and IV

3. Which of the following substances can be used to differentiate ethane from ethane?

A. Lime waterB. Bromine waterC. Dilute sulphuric acidD. Sodium hydroxide solution

4. What are the products formed when propene burns completely in excess air?A. Water and carbon dioxide gas

B. Water, carbon and carbon dioxideC. Water, carbon monoxide gas and carbon dioxide gasD. Water, carbon, carbon monoxide gas and carbon dioxide gas

9

5. Which of the following pairs of compound are in the same homologous series? A. C5H10, C6H14

B. C5H12, C7H16

C. C3H6, C5H12

D. C4H8, C6H14

6. What is the name of compound above?A. 2-ethylpent-4-enaB. 3-ethylbut-1-enaC. 3-methylbut-1-enaD. 2-methylbut-4-ena

B. Structured question:

A hydrocarbon K contains 82.76% mass of carbon. In nature, hydrocarbon K is mixed with other hydrocarbons.

(a) Name two important sources of hydrocarbon.

(b) Based on the information above, determine the empirical formula for K.(Relative atomic mass: H,1 ; C, 12)

(c) If 5.8 g of K contains 6.02 x 1022 molecules, determine the(i) Relative molecular mass for K(ii) Molecular formula for K

(Avogadro number: 6.02 x 1023 mole-1)

(d) Write the general formula for K and state its homologous series.

(e) Draw a structural formula for the isomers of K and name them.

(f) In an experiment 40 cm3 K gas and 360 cm3 oxygen gas are mixed together.

(i) Write the equation for the reaction between hydrocarbon K and oxygen gas.

(ii) What is the gas volume after cooling the products at room temperature

(iii) What is the volume of gas that is left if the mixture of gases in f (ii) going through saturated potassium hydroxide solution.

( 1 mole gas = 24 dm3 at room condition)

10

C. Essay question:

+ H2

Heat

(a) The information below is regarding alkene Y:

Carbon 85.7 % Hydrogen 14.3% Relative molecular mass = 42 Jisim atomic mass of H = 1 and C =12

Based on the information of the alkene Y:(i) Determine the molecular formula(ii) Draw the structural formula

(iii) Name the alkene(iii) Write the general formula for its homologous series

(b) Table below shows the results of atest to differentiate between alkene Y and propane

Procedure ObservationBromine water is added to alkene Y

Brown colour is decolourized

Bromine water is added to propane

Brown colour remains

Explain why there is difference in these observations.

Activity 1

11

Propane Alkene Y

ANSWERS FOR ACTIVITY

Substance Organic compound Inorganic compoundSugar /Amino acids /Carbon dioxide gases /Copper(II) carbonate /Latex /Hydrogen cynide /

TABLE 1Activity 1.2

Physical Properties True False1. Physical properties of alkanes change gradually when the number of carbon atoms

/

2. Melting point of alkanes decrease with the increasing number of carbon atoms per molecule.

/

3. Alkanes compound dissolve in water /4. Alkanes conduct electricity /5. Density of alkanes increase with the increasing number of carbon atoms per molecule.

/

6. Butane, C4H10 exist in gases state at room temperature /

Activity 1.3

combustion combustion

+ excess O2 + limited O2

+ Cl2 Subtitution reaction

Activity 1.4

Description Match AnswerAn unsaturated hydrocarbon Homologous seriesA group of organic compounds related by their structure

Alkene

Addition of a molecule to the carbon, C atoms of a double bond

Addition reaction

Activity 1.5

Molecular formulaButane, C4H10

2 isomersButene, C4H8

3 isomersPentene, C5H12

5 isomers

12

Ethane, C2H6

C2H5Cl

CO + H2OCO2 + H2O

STRUCTURAL

FORMULAE

A. Objective Question

1. B2. C3. B4. A5. B6. C

B. Structured Question

13

ANSWERS FOR ASSESSMENT

(a) Petroleum and natural gas

(b) Element Carbon HydrogenMass 82.76 17.24No. of mole 82.76 = 6.9

1217.24 = 17.24 1

Ratio of mole 6.9 = 16.9

17.24 = 2.5 6.9

Simplest ratio 1 x 2 = 2 2.5 x 2 = 5

Empirical formula for K is C2H5

(c) Mole = 6.02 x 10 22 = 0. 1 6.02 x 10 23

0.1 mole → 5.8 g 1 mole → 1 x 5.8 0.1 = 58g

Relative molecular mass for K = 58

[ C2H5]n = 58 [ (12 x 2) + (5 x 1)]n = 58 [24 + 5]n = 58 29n = 58 n = 2 Molecular formula for K = [C2H5]2 = C4H10

(d) Homologous series = alkanes

(e)

n-butane

2-metilpropane

(f) (i) 2C4H10 + 13O2 → 8CO2 + 10H2O

(ii) Mole K = 40 . = 1.67 x 10-3

24000Mole O2 = 360 . = 0.015 24000

14

From the equation; 2 mole C4H10 react with 13 mole O2

1.67 x 10-3 mole C4H10 → 1.67 x 10 -3 x 13 2 = 0.011 mole O2

Mole O2 excess = 0.015 - 0.011 = 0.004 mole

From the equation; 2 mole C4H10 produce 8 mole CO2

1.67 x 10-3 mole C4H10 → 1.67 x 10 -3 x 8 2 = 6.68 x 10-3 mole CO2

Gas volume = (mole O2 excess + mole CO2 produce) x 24 dm3

= (0.004 + 6.68 x 10-3) x 24 dm3

= 0.256 dm3

= 256 cm3

(iii) Potassium hydroxide solution dissolve CO2

Volume of gas = 0.004 x 24 dm3

= 0.096 dm3

= 96 cm3 C. Essay:

(a) (i)Element Carbon HydrogenMass 85.7 14.3No. of mole 85.7 = 7.14

1214.3 = 14.3 1

Ratio of mole 7.14 = 17.14

14.3 = 2 7.14

Simplest ratio 1 2

Empirical formula = CH2

[ CH2]n = 42[ 12 + 2(1) ]n = 42[ 24 ]n = 24n = 2

Molecular formula = [ CH2 ]2 = C2H4

(ii)

(iii) Ethene

15

(iv) CnH2n

(b)

Alkanes not react with halogens, Br2 because alkanes are saturated compound (single bond).

Alkenes react with halogens, Br2. This reaction is addition reaction. In an addition reaction, a molecule is ‘added’ to the two carbon, C atoms of a double bond. One of the bonds that is part of the double bond between the carbon, C is

broken. The pair of electrons that forms this bond is then shared with the molecule

that is ‘added’. The product is a saturated compound.

16