Chemistry Topic 7 - Organic Chemistry

Question 1

What is crude oil?

Answer 1

A mixture of compounds; a fossil fuel of the remains of ancient biomass

Finite resource - cannot be replaced as it is used up

Question 2

What is a hydrocarbon?

Answer 2

A compound made up exclusively of hydrogen and carbon atoms

Question 3

What is a homologous series?

Answer 3

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

Question 4

describe the combustion of hydrocarbons

Answer 4

-exothermic reaction occurring when hydrocarbons are reacted with oxygen
-complete combustion produces carbon dioxide and water
-incomplete combustion produces carbon or carbon monoxide and water

Question 5

Describe the physical properties of alkanes

Answer 5

-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 6

What is cracking?

Answer 6

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

Question 7

What type of reaction is cracking?

Answer 7

Thermal decomposition

Question 8

what are the conditions for cracking?

Answer 8

Reactants heated to vapour, passed over a hot catalyst or heated to vapour, mixed with steam and heated to high temperatures

Question 9

How are the products of cracking used?

Answer 9

The products of alkanes and alkenes - used as polymers and starting materials from synthesis

Question 10

What is the test for alkenes?

Answer 10

Add bromine water
Colour change occurs from orange to colourless

Question 11

Describe the combustion of alkenes

Answer 11

They burn with smoky flames due to incomplete combustion

Question 12

What is an alcohol?

Answer 12

An organic compound that contains an -OH functional group

Question 13

State characteristics of methanol, ethanol, propanol and butanol

Answer 13

-dissolve in water to from a neutral solution
-react with sodium to form hydrogen
-burn in oxygen
-react with carboxylate acids in presence of acid catalyst to form esters

Question 14

Oxidation of the alcohols leads to…?

Answer 14

Carboxylic acids

Question 15

What are some uses of alcohols?

Answer 15

-fuels
-solvents
-drinks

Question 16

What are carboxylic acids?

Answer 16

Organic compounds that constrain a COOH functional group

Question 17

State characteristics of carboxylic acids

Answer 17

-dissolve in water to form an acidic solution
-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 18

What type of acid is carboxylic acid?

Answer 18

It is a weak acid

Question 19

Explain why carboxylic acids are weak acids?

Answer 19

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 concerntration

Question 20

What is an ester and how did it form?

Answer 20

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

Question 21

What is a polymer? How do molecules containing C=C bond form polymers?

Answer 21

A polymer is along chain molecules which is made by lots of smaller molecules joining together
C=C bonds open up and many smaller molecules join together to form a chain. No other products are made
It is called an “addition polymerisation” reaction

Question 22

What is a repeating unit of a polymer?

Answer 22

It is a smaller structure which, upon numerous translations, yields the structure of the polymer.
In addition polymers: to draw it, take a monomer, change C=C to C-C and show additional single bonds extending away from these carbons.

Question 23

What is an amino acid?

Answer 23

It is an organic compound that contains both a carboxylic acid functionally (COOH) and an amine functional group

Question 24

What are carbohydrates?

Answer 24

They are organic molecules made of C,H and O. They are biologically relevant

Question 25

What is DNA ? Describe its role and structure

Answer 25

DNA Is a material that makes up chromosomes-cell structures that store genetic information

DNA is made up of two polymer chains that are held together in a double helix

Each polymer chain can be made from 4 different monomers - nucleotides