Life Science

Question 1

Organic chemistry

Answer 1

the study of the preparation, reactions, properties, structure and composition of the carbon containing compound

Question 2

Saturated compound

Answer 2

It is a compound where all the bonds in carbon atoms are single bonds

Question 3

Hydro carbons

Answer 3

compound containing hydrogen and carbon atoms

Question 4

give examples of hydrocarbns

Answer 4

alkanes and alkenes

Question 5

example of a saturated organic compound

Answer 5

alkanes

Question 6

Unsaturated compound

Answer 6

compound where the bonds in the carbon atoms are double or triple bond.

Question 7

example of unsaturated compound

Answer 7

alkene

Question 8

functional group

Answer 8

it is an atom or group of atoms that form the centre of a chemical activity in the molecule

Question 9

homologous series

Answer 9

Group of organic compounds that have the same characteristics

Question 10

what are the 5. characteristics that a the homologous series have

Answer 10

a. have same functional group
b. have same chemical properties
c. prepared with the same method
d. conform to same general formula
e. succesive members differ by -ch2 unit

Question 11

Isomers

Answer 11

Organic compounds with the same molecular formula but different structural formula

Question 12

types of isomers

Answer 12

a. chain isomer.
b. functional isomers
c. postional isomers

Question 13

General fromula for alkanes

Answer 13

CnH2n+2

Question 14

normen clature

Answer 14

the naming of organic compounds

Question 15

describe Physical properties of alkanes

Answer 15

Physical properties gradually change as number of atoms increase due to increase in strength of london forces

Question 16

Boiling points of alkanes

Answer 16

branched alakanes have a less boiling pount that straight chained alkanes because branched alaknes have less surface area of contact between molecule resulting in weak london forces.

Question 17

Sources of alkanes

Answer 17

a. natural gas.
b. crude oil.
c. petroleum

Question 18

what are the physical properties of alkanes

Answer 18

a. colourless
b. less dense than water.
c. non polar molecules which means they are soluble in non polar solvents.
d. they are flammable

Question 19

alkanes show which isomerism

Answer 19

chain and postional

Question 20

Chemical properties of alkanes

Answer 20

Alkanes are unrecative hydrocarbons beacuse they are saturated organic compounds.

Question 21

what are the reactions alkanes goes through

Answer 21

combustion and subtitution with halogens

Question 22

what is combustion of alkanes

Answer 22

alkanes burn well with oxygen producing carbon dioxide, water and heat energy. which is why they are used as fuels.

Question 23

Alkanes reacation with halogen

Answer 23

it is called substitution then the specific thing is halogenation.(hydrogen atoms are replaced by halogen atoms)

Question 24

Alkanes react with halogens in the presence of what?

Answer 24

presence of uv lights producing hydrogen halides and halogen alkanes

Question 25

use of alkanes

Answer 25

fuel.

Question 26

Exxplain the physical properties of alkenes

Answer 26

Physical properties of alkenes change gradually as carbonatoms increase due to increase in strength of london forces

Question 27

Boiling points and melting points of alkenes

Answer 27

Branched alkenes have low melting points and low boiling points than straight chain alkenes because they have less surfcae area contact between molececules which results in weak london forces

Question 28

what isomerism does alkenes show

Answer 28

chain, functional,position isomeism

Question 29

Sources of alkens

Answer 29

a. cracking b. dehydraton of alchol using concenrated sulfuric acid(deydration and elmination) c. halogen alkanes react with alcohlic sodium hydroxide or potassium hydroxide(eliminaation and dehydrohalogenation

Question 30

what is cracking

Answer 30

breaking down of long chains of alkane molecule using heat and catalyst into shorter chains and more useful ones cracking produces shorter alkanes and alkenes

Question 31

Chemical properties of alkenes

Answer 31

they are reactive beacuse they are unsaturated, the double bonds act like source of elctrons therefore they undergo addition reactions.

Question 32

Alkenes undergo which 5 reactions

Answer 32

a. combustion b. addition of hydrogen. c. reaction with steam d. reaction with bromine e. reaction with hydrogen halides

Question 33

decribe the reaction of alkene and hydrogen

Answer 33

it is an addition reaction. specific is hydrogenation alkene react with hydrogen in presence of heat pressure and catalyst.

Question 34

describe reacation of alkene with steam

Answer 34

alkenes reacts with steam in presence of heat forming alchol, catalyst, phosphoric acid addition reaction and hydration

Question 35

Describe reaction of alkene and bromine

Answer 35

Alkenes reacting with bromine water decolourises the water. process is used for distingishing alkanes and alkenes it tests the unsaturation in organic compounds bromine shake with alkenes watere becomes colourless. alkanes cannot addition reaction or halogenation

Question 36

Reaction with hydrogen halide

Answer 36

alkene reacts with hydrogen halide forming halogen alkanes

Question 37

Halogen alkanes

Answer 37

1 or more hydrogen atoms of alkanes are replaced by a halogen

Question 38

what are the sources of halogenalkanes

Answer 38

a. reaction between hydrogen halides and alkenes b. reaction with alkane and hydrogen in prsence of uv light c. alkenes react with halogens.

Question 39

Physical properties og haloalkanes

Answer 39

B.P increases due to increase in van der waal forces. halo alkanes have a higher boiling point than alkanes and alkenes because they are polar molecules therefore they have strong van der waal forces than alkanes and alkenes of the same length.

Question 40

Chemical properties of haloalkanes

Answer 40

very reactive due to presence of halogen in the molecules reaction happens on carbon carry the halogen atom undergo substitution reaction where halogen atom is replaced by othe atoms

Question 41

Reaction that haloalkanes go through

Answer 41

a. reaction with water and koh or naoh | b. elimination reaction

Question 42

describe the reaction of water and koh or naoh for haloaknaes

Answer 42

water and koh an naoh react forming alchols(hydrolosis) and subtituition

Question 43

elimination reaction

Answer 43

reaction is undergone is presense of koh an naoh. hydrogen and halogen atoms are removed from carbon resulting in formation of double bonds between carbons (dehydrohalogenation)

Question 44

Alcohol/hydoxyl compounds

Answer 44

Oh bonded to carbon function group OH