organic chemistry Flashcards

1
Q

What is crude oil?

A

Crude is a mixture of compounds; a fossil fuel consisting of the remains of ancient biomass.

Finite resource - cannot be replaced as it is used up.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a hydrocarbon?

A

A compound made up exclusively of hydrogen an carbon atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are alkanes?

A

Saturated hydrocarbons of a general formula CnH2n+2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a homologous series?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the combustion of hydrocarbons

A
  • Exothermic reaction occurring when hydrocarbons are reacted with oxygen.
  • complete combustion produces carbon dioxide an water (carbon and hydrogen atoms are completely oxidised).
  • Incomplete combustion produces carbon or carbon monoxide and water.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the physical properties of alkanes

A
  • First few in series are gasses, then changes to liquid, then to solids.
  • In general, boiling points and viscosity increases as molecules get bigger.
  • Volatility and flammability decreases as molecules get bigger.
  • Poor reactivity.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Explain how fractional distillation of crude oil takes place

A
  • Crude oil is heated and vapourised.
  • Vapour 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 condenses at different hights, 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.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is cracking?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What type of rection is cracking?

A

Thermal disposition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the conditions for cracking?

A

reactant heated to vapour, passed over a hot catalyst (catalytic cracking) or heated to vapour, mixed with steam and heated to high temperatures (steam cracking)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are the products of cracking used?

A

The products are alkanes and alkenes - used as polymers and starting materials for synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is an alkene?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the test for alkenes?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the combustion alkenes

A

They burn with smoky flames due to incomplete combustion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the addition reaction of alkenes

A

Addition atoms the carbon-carbon double bond becomes a single carbon-carbon bond.
a) With hydrogen - hydrogenation; requires a higher temperature and a nickel catalyst
b) With steam - hydration; requires high temperature, pressure, and contracted phosphoric acid (H3PO4) as a catalyst
c) With Br2/Cl2/I2 - addition of halogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an alcohol?

A

An organic compound that contains an -OH functional group

17
Q

State characteristics of methanol, ethanol, propanol and butanol

A
  • 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.
18
Q

Oxidation of the alcohols leads to…?

A

Carboxylic acids

19
Q

What are some uses of alcohols?

A
  • Fuels
  • Solvents
  • Drinks
20
Q

State the conditions required for fermentation of glucose and state the equation of the reaction

A

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

C6H12O6 -> 2CH3CH2OH+2 CO2

21
Q

What are carboxylic acids?

A

Organic compounds that contain a COOH functional group

22
Q

State characteristics of carboxylic acids

A
  • 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
23
Q

What type of acid is carboxylic acid?

A

It is a weak acid.

24
Q

Explain why carboxylic acids are weak acids?

A

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.

25
Q

What is an ester and how is it formed? What is characteristic about this class of compounds?

A

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

They have a fruity smell.

26
Q

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

A

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

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

It is called an “addition polymerisation” reaction.

27
Q

Give 3 examples of addition polymers and their uses.

A

Polyethene - plastic bags

(Poly)tetrafluoroethene (PTFE) - teflon surfaces, for use in non-stick kitchenware
(Poly)chloroethene (polyvinylchloride, PVC) - water pipes

28
Q

What is a repeating unit of polymer?

A

It is a smallest structure which, upon numerous translation, 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.

29
Q

What is a condensation polymer? How is it made? There are 2 main groups - name them and give industrially relevant examples.

A

It is a polymer made in condensation polymerisation.

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

Polyesters, e.g. terylene.

Polyamides, e.g. Nylon.

30
Q

What is an amide bond?

A

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.

31
Q

What is an amino acid?

A

It is an organic compound that contains both a carboxylic acid functionality (COOH) and an amine functional group (-NH2).

32
Q

How do amino acids make proteins? What are polypeptides? What are polypeptides?

A

By numerous condensation polymerisation reaction; proteins are polymers made amino acids (monomers).

*Polypeptides are also made by condensation polymerisation of amino acids, but are shorter than proteins. One could think about proteins as a product of many polypeptide chains bonded together.

33
Q

What are carbohydrates?

A

They are organic molecules made of C,H, and O. They are biologically relevant, e.g. starch and cellulose.

Both of these are polymers made of glucose (other carbohydrate) monomers. Their structures differ in the same way the glucose molecules are joined together.

34
Q

What is DNA? Describe its role and structure.

A

DNA (deoxyribonucleic acid) is a material that makes up chromosomes - cell structures that store genetic information.

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

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