organic chemistry

Question 1

what is the definition of hydrocarbon

Answer 1

hydrocarbon are organic compounds that contain hydrogen and carbon

Question 2

what are the sources of fossil fuels

Answer 2

1.decayed plants & animals
2. organic compounds such as fossil duels and carbon
3. fossil fuels are burnt in presence of oxygen = combustion

Question 3

what are the types of fossil fuels

Answer 3

1. crude oil
2. natural gases
3. coal

Question 4

where is crude oil found

Answer 4

crude oil is found in sea beds or underground on land

Question 5

where are natural gases found

Answer 5

methane found in crude oil

Question 6

where is coal found

Answer 6

mainly carbon

Question 7

define petroleum (crude oil)

Answer 7

petroleum is aliquid mixture of hydrocarbons

Question 8

what method is used to separate crude oil/ petroleum

Answer 8

fractional distillation

Question 9

what us the abbreviation for crude oil

Answer 9

pretty people never kiss dirty looking boys

Question 10

what are the substances obtained from crude oil

Answer 10

petroleum
petrol
naphtha
kerosene
diesel oil
lubricating oil
bitumen

Question 11

are fractions pure substances

Answer 11

fractions are a mixture of substances that re not pure as they have varying boiling point

Question 12

state the relation btw length and size of hydrocarbons and boiling point

Answer 12

the longer the hydrocarbon, the bigger the hydrocarbon the higher the boiling point

Question 13

why is fractional distillation important for crude oils

Answer 13

as different fractions have different purposes

Question 14

what are biofuels

Answer 14

biofuels are renewable energy sources that come from animals and plants

Question 15

what is the process to obtain biofuels

Answer 15

biofuels burn = CO2 produce = absorbed by photosynthesises by sugar canes = no excess CO2 produced

Question 16

how are biofuels obtained

Answer 16

by fermenting sugar in sugarcane plants

Question 17

what is the definition of homologues series

Answer 17

a group of organic compounds with the same general formula, same functional group having similar chemical properties and consecutive member differing from each other by a -CH2- unit

Question 18

what are the characteristics of crude oil

Answer 18

1. general formula
2. differs by -CH2- unit
3. same functional group = same properties
4. similar reactions
   5.gradual change in physical properties as molecular size inc

Question 19

what are the physical properties of homologues series

Answer 19

melting and boiling point
flammability
viscosity
density
solubility in organic solvent

Question 20

name the 1st 3 alkanes, name and no. of atoms

Answer 20

1, methane
2. ethane
3, propane

Question 21

what is a functional group

Answer 21

specific atoms bonded in certain arrangement that give a compound certain physical and chemical property

Question 22

what is the definition of alkanes

Answer 22

alkanes are saturated hydrocarbons which have a c-c single bond

Question 23

what is the general formula of alkanes

Answer 23

CnH2+2

Question 24

what is the source of alkanes

Answer 24

crude oils

Question 25

what is the structure of alkanes

Answer 25

simple covalent molecular structure

Question 26

what is the physical properties of alkanes

Answer 26

low melting and boiling point due to simple covalent molecular structure with weak forces of attraction

solubility in organic solution

Question 27

what are the chemical reactions of alkanes

Answer 27

1. combustion
2. substitution
3. cracking

Question 28

how does complete combustion work with alkanes

Answer 28

alkanes are burnt in the presence of excess oxygen to produce CO2 and H2O = complete combustion

Question 29

how does incomplete combustion work with alkanes

Answer 29

alkanes burn in the presence of limited oxygen to produce CO and H2O

Question 30

how does substitution work with alkanes

Answer 30

substitution is the reaction of saturated compounds & catalysed under the presence of uv light

Question 31

what is the definition of substitution

Answer 31

substitution is the process of an atom replaced by another atom or group of atoms

Question 32

what is the reaction given substitution

Answer 32

methan + cl =

Question 33

what is the definition of cracking

Answer 33

cracking is process where larger hydrocarbon molecules are broken down into smaller hydrocarbon molecules

Question 34

what are the conditions needed for cracking

Answer 34

1. solid catalyst
2. high temperature

Question 35

state the 2 general equations in cracking

Answer 35

large alkane = small alkene + small alkane

large alkane = small alkene + H2

Question 36

what is the importance of cracking

Answer 36

during fraction distillation of crude oil, large amount of the nigger alkanes molecules is obtained . cracking is important to the higher demands of fractions containing smaller molecules

Question 37

what does cracking provide

Answer 37

high quality gasoline
important raw materials - ethane and propane
source of hydrogen to make ammonia to make fertilizers

Question 38

what are the uses of alkanes

Answer 38

use as fuels
methane = main natural gas
alkanes = alkenes by cracking