c7 - organic chemistry

Question 1

What is crude oil?

Answer 1

Crude oil is a mixture of hydrocarbons

Question 2

what is crude oil made from

Answer 2

a fossil fuel consisting of the remains of ancient biomass

Question 3

What is a hydrocarbon?

Answer 3

A compound made up exclusively of hydrogen and carbon atoms

Question 4

what are alkanes

Answer 4

Saturated hydrocarbons of a general formula CnH2n+2

Question 5

What is a homologous
series?

Answer 5

Series of compounds with same general formula, same functional groups and
similar chemical properties.

Question 6

Describe the combustion of
hydrocarbons

Answer 6

• Exothermic reaction occurring when hydrocarbons are reacted with oxygen.
• Complete combustion produces carbon dioxide and water (carbon and
  hydrogen atoms are completely oxidised).
• Incomplete combustion produces carbon or carbon monoxide and water.

Question 7

Describe the physical
properties of alkanes

Answer 7

• First few in series are gases, then change to liquids, then to solids.
• In general, boiling points and viscosity increase as molecules get bigger.
• Volatility and flammability decrease as molecules get bigger.
• Poor reactivity

Question 8

Explain how fractional
distillation of crude oil takes
place

Answer 8

• Crude oil is heated and vaporised.
• Vapor rises up the fractionating column (tower).
• The column is hotter at the bottom and cooler at the top.
• Hydrocarbons cool as they go up the column and condense at
  different heights, as they have different boiling points.
• Large molecules, high boiling points - collected at the bottom.
• Small molecules, low boiling points - collected at the top.
• This gives fractions, which can be used in various ways.

Question 9

What is cracking?

Answer 9

When large hydrocarbons are thermally broken down into smaller and useful
molecules

Question 10

What type of reaction is cracking?

Answer 10

thermal decomposition

Question 11

What are the conditions for cracking?

Answer 11

steam
hot catalyst (aluminum oxide)
high temperatures

Question 12

How are the products of cracking used?

Answer 12

to keep up with demand

Question 13

What is an alkene?

Answer 13

Unsaturated hydrocarbon. Contains a C=C bond.
General formula for alkenes is: CnH2n.

Question 14

What is the test for alkenes?

Answer 14

Add bromine water. Colour change occurs from orange to colourless.

Question 15

Describe the combustion of
alkenes

Answer 15

They burn with smoky flames due to incomplete combustion

Question 16

describe the basic addition reactions of alkenes

Answer 16

the double bond
becomes a single carbon-carbon bond.

Question 17

alkenes reaction with hydrogen

Answer 17

hydrogenation; requires a higher temperature and a nickel
catalyst

Question 18

alkenes reaction with steam

Answer 18

hydration; requires high temperature, pressure, and
concentrated phosphoric acid (H3PO4) as a catalyst

Question 19

What is an alcohol?

Answer 19

An organic compound that contains an -OH functional group

Question 20

State characteristics of
methanol, ethanol, propanol
and butanol

Answer 20

• Dissolve in water to form a neutral solution.
• React with sodium to form hydrogen.
• Burn in oxygen.
• React with carboxylic acids in presence of acid catalyst to form esters.

Question 21

Oxidation of the alcohols leads to…?

Answer 21

Carboxylic acids

Question 22

What are some uses of alcohols?

Answer 22

• Fuels
• Solvents
• Drinks

Question 23

State the conditions required for fermentation of glucose

Answer 23

30 degrees Celsius,
aqueous solution of the glucose, absence of air,
yeast added;

Question 24

equation for fermentation

Answer 24

C6H12O6 → 2 CH3CH2OH + 2 CO2

Question 25

What are carboxylic acids?

Answer 25

Organic compounds that contain a COOH functional group

Question 26

State characteristics of carboxylic acids

Answer 26

- Dissolve in water to form an acidic solution (contains H+ ions) - React with metal carbonates to form carbon dioxide - React with alcohols with an acid catalyst to produce esters - React with metals to give off hydrogen gas

Question 27

What type of acid is carboxylic acid?

Answer 27

weak

Question 28

Explain why carboxylic acids are weak acids?

Answer 28

They are partially dissociated in water, thus the pH of a carboxylic acid in solution is not as low as a solution of a strong acid of the same concentration.

Question 29

What is an ester and how is it formed?

Answer 29

An organic compound containing a -COO- functional group, formed from carboxylic acid and alcohol in the presence of a sulfuric acid catalyst.

Question 30

charateristic of this compound

Answer 30

fruity smell

Question 31

What is a polymer?

Answer 31

A polymer is a long chain molecule which is made by lots of smaller molecules joining together.

Question 32

what is additional polymerisation

Answer 32

C=C bonds open up and many smaller molecules (monomers) join together to form a chain (a polymer). No other products are made.

Question 33

Give 3 examples of addition polymers and their uses.

Answer 33

Polyethene - plastic bags (Poly)chloroethene - water pipes

Question 34

What is a condensation polymer?

Answer 34

It is a polymer made in condensation polymerisation

Question 35

how is a condensation polymer made

Answer 35

many molecules join together; the polymer is formed, but also a small molecule is released, e.g. H2O, HCl.

Question 36

two examples of condesation polymers

Answer 36

Polyesters, e.g. terylene. Polyamides, e.g. Nylon.

Question 37

What is an amide bond?

Answer 37

An amide bond is similar to the ester bond, with O replaced by N, e.g. (C=O)-NH2 Just like an ester, it contains the C=O group