organic chemistry Flashcards

1
Q

What is crude oil?

A

crude oil is a mixture of compound; 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 and 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 C n H 2n+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 the 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 and 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 gases, then change to liquids then to solids

In general boiling points and viscosity increases as molecules get bigger

volatility and flammability decrease 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 vaporised
-Vapour rises up the fractionating column
-The column is hotter at the bottom and cooler at the top
-Hydrocarbons as they go up the column and condensed at different height, 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 reaction is cracking?

A

Thermal decomposition

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 or heated to vapour, mixed with steam and heated to high temperatures

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 changes occur from orange to colourless.

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

describe the combustion of 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 addition reactions of alkenes

A

addition atoms across the carbon – carbon double bond so that the double bomb becomes a single carbon – carbon bond

a) with hydrogen-hydro generation; requires a high temperature and a nickel catalyst
b) with steam-hydration; requires high temperature, pressure and concentrated phosphoric acid as a catalyst
c)with Br2/Cl2/I2

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
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 acid in presence of acid catalyst to form Esther

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Oxidation of the alcohol 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°C, aqueous solution of the glucose, absence of air, yeast added

C6H12O6 —-> 2 CH3 CH2 OH + 2CO2

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 alcohol within an acid catalyst produce Esters
-React with metals to give off hydrogen gas

23
Q

what type of acid is carboxylic ackd

A

it is a weak acid

24
Q

Explain my carboxylic acids are weak acids

A

they are partially dissociated in water, thus the pH of 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

A

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

They have a fruity smell

26
Q

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

A

A polymer is a longchain molecule which is made by lots of smaller molecules joining together

C=C bond and many smaller molecules joined together to form a chain. No other products are made.

It is called an (addition polymerisation) reaction

27
Q

give free examples of addition polymers and their uses

A

Polythene-plastic bags

28
Q

What is a repeating unit of a 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 additional single bonds extending away from these carbons

29
Q

akene + water

A

alkanes
-hydrogenation

30
Q

alkenes+water

A

alcohol
-hydration

31
Q

alkenes + halogen

A

haloalkane

32
Q

what happens if you react alcohol with
-sodium
-oxygen
-water

A

sodium-fizzes
oxygen-burns
water-dissolves

33
Q

equation for fermentation

A

sugar ——> ethanol + carbon dioxide
yeast 37

34
Q

what happens if you react carboxylic acid
-carbonates
-alcohols

A

carbonates-fizzes
alcohols-esters

35
Q

make ethene a polymer

 |   | n   C=C
  |   |
  h   h
A

break the carbon double bond

[-C-C-]

add brackets with n outside

36
Q

what’s the diffrence between a poly ethene displayed formula and polypropene

A

C=C.
has CH3 in the corner

37
Q

How can large hydrocarbons molecules be cracked in an oil refinery?

A

A heavy fraction distilled from crude oil is heated to vaporise the heat hydrocarbons the vapour is then

passed over hot catalyst
or mix with steam and heated a very high temperature 

38
Q

what type of reaction is cracking an example of?

A

Thermal decomposition

39
Q

why is crude oil not very useful as a product itself?

A

There are too many substances with all different boiling points

40
Q

Why are alkanes described as saturated hydrocarbons?

A

They contain as much hydrocarbon atoms as possible

41
Q

Name the products of the complete combustion of a hydrocarbon

A

carbon dioxide + water

42
Q

describe a positive test for each of the products of combustion

A

White anhydrous copper sulphate with water and the white powder turns blue

43
Q

explain the steps involved in the fractional distillation of crude oil

A

 crude oil is separated into hydrocarbons with similar boiling points called fractions

Each hydrocarbon fraction contains molecules with similar number of carbon atoms each of these fractions boil at different temperature range because of the different sizes of molecules in it

Is heated and fed bottom of the tall tower as hot vapour. The column is kept very hot at the bottom much cooler than the top to the temperate decreases going up the column.

44
Q

how do the size of a hydrocarbon molecule affect?

The boiling point
The volatility
The viscosity of a hydrocarbon

A

boiling point -increases
volatility-decreases
viscosity-increase
flammability-decreases