Organic Chemistry

Question 1

What is a hydrocarbon?

Answer 1

A compound of hydrogen and carbon only

Question 2

What is a saturated hydrocarbon?

Answer 2

A hydrocarbon containing no double C bonds

Question 3

What is an unsaturated hydrocarbon

Answer 3

A hydrocarbon containing double C bonds

Question 4

What is general formula

Answer 4

An algebraic formula that can describe any member of a family of compounds

Question 5

What is empirical formula

Answer 5

The simplest whole number ratio of atoms of each element in a compound

Question 6

What is molecular formula

Answer 6

The actual number of atoms of each element in a molecule

Question 7

What does displayed formula show

Answer 7

How all the atoms are arranged and all the bonds between them

Question 8

What does structural formula show

Answer 8

The arrangement of atoms carbon by carbon with the attached hydrogens and functional groups

Question 9

What is a homologous series

Answer 9

A group of compounds that can all be represented by the same general formula

Question 10

Do compounds in a homologous series share similar chemical properties?

Answer 10

Yes

Question 11

What is the general formula for alkanes?

Answer 11

CₙH₂ₙ₊₂

Question 12

What is the general formula for alkenes?

Answer 12

CₙH₂ₙ

Question 13

What is a functional group?

Answer 13

A group of atoms that determine how a compound typically reacts

Question 14

What is isomerism?

Answer 14

Isomerism is when compounds have the same molecular formula but different structures

Question 15

What is the stem for 1 carbon

Answer 15

Meth

Question 16

What is the stem for 2 carbon

Answer 16

Eth

Question 17

What is the stem for 3 carbon

Answer 17

Prop

Question 18

What is the stem for 4 carbon

Answer 18

But

Question 19

What is the stem for 5 carbon

Answer 19

Pent

Question 20

What is the stem for 6 carbon

Answer 20

Hex

Question 21

What is an isomer

Answer 21

A molecule with the same molecular formula but different displayed formula

Question 22

What is crude oil

Answer 22

A mixture of hydrocarbons

Question 23

How is crude oil separated into different fractions?

Answer 23

Crude oil is heated and vaporized. In a fractional distillation column, different fractions condense at different levels based on boiling points

Question 24

What is bitumen used for

Answer 24

Surfacing roads
Roofs

Question 25

What is fuel oil used for

Answer 25

Fuel for ships and power stations

Question 26

What is diesel used for

Answer 26

Fuel in cars / larger vehicles

Question 27

What is kerosene used for

Answer 27

Aircraft fuel

Question 28

What is gasoline used for

Answer 28

Fuel in cars

Question 29

What is refinery gases used for

Answer 29

Domestic heating and cooking

Question 30

What is the trend in colour when the fractions of crude oil are burned?

Answer 30

As you go down, the fractions get darker. This happens because heavier fractions have larger, more complex molecules that absorb more light.

Question 31

Explain the trend in boiling point for the fractions of crude oil

Answer 31

Boiling points increase as you go down. Lighter fractions have lower boiling points because their smaller molecules need less energy to separate, while heavier fractions need more energy due to larger molecules

Question 32

Explain the trend in viscosity for the fractions of crude oil

Answer 32

Viscosity increases as you go down. Lighter fractions are less viscous, while heavier ones are thicker due to stronger intermolecular forces between larger molecules

Question 33

Explain the trend in cleanliness of the flame when burning the fractions of crude oil

Answer 33

Cleanliness decreases as you go down. Lighter fractions burn cleanly with a blue flame, while heavier ones burn with a yellow, smoky flame because they have more carbon and produce soot

Question 34

What is fuel

Answer 34

A substance that, when burned, releases heat energy

Question 35

What is the formula for the complete combustion of hydrocarbons

Answer 35

hydrocarbon + oxygen -> carbon dioxide + water

Question 36

What is the formula for the incomplete combustion of hydrocarbons

Answer 36

Hydrocarbon + Oxygen → Carbon monoxide + Carbon (soot) + Water

Question 37

When are nitrogen oxides created

Answer 37

When the temperature is high enough for the nitrogen an d oxygen in the air to react (i.e. inside car engines)

Question 38

How does the combustion of some impurities in hydrocarbon fuels result in the formation of sulfur dioxide?

Answer 38

Hydrocarbons with sulfur impurities release sulfur when burned. The sulfur reacts with oxygen in the air to form sulfur dioxide (SO₂), a harmful gas

Question 39

How do sulfur dioxide and nitrogen oxides contribute to acid rain?

Answer 39

When sulfur dioxide and nitrogen oxides mix with water vapour in clouds they form dilute sulfuric acid and nitric acid

Question 40

What is cracking?

Answer 40

A form of thermal decomposition in which large hydrocarbons are broken down into smaller hydrocarbons

Question 41

Describe catalytic cracking

Answer 41

Vaporised hydrocarbons are passed over a powdered catalyst (600-700 degrees). Silica or alumina used as catalyst.

Question 42

Why is cracking used

Answer 42

Demand for short-chain hydrocarbons is much higher than large-chain Some hydrocarbons are not found in crude oil but can be obtained through cracking

Question 43

Are alkenes more valuable than alkanes?

Answer 43

Yes

Question 44

Why are alkenes more valuable than alkanes?

Answer 44

Alkenes are more reactive and can be used to make products like plastics, while alkanes are mainly used as fuels

Question 45

Describe the reaction of alkanes with halogens in ultraviolet radiation

Answer 45

Undergo a substitution reaction, where a hydrogen atom is replaced by a halogen atom

Question 46

What is the functional group in alkenes?

Answer 46

C=C

Question 47

Describe the reactions of alkenes with bromine

Answer 47

Alkenes react with bromine in an addition reaction, where the double bond breaks and a bromine atom attaches to each carbon, forming a dibromoalkane

Question 48

How can bromine water be used to distinguish between an alkane and an alkene?

Answer 48

Bromine water is decolorized by alkenes, due to their double bond reacting with bromine. Alkanes, however, do not react and the bromine water stays orange/brown