organic chemistry

Question 1

What is crude oil made from?

Answer 1

The remains of an ancient biomass consisting mainly of
plankton that was buried in mud

Question 2

What are alkanes?

Answer 2

Hydrocarbons that contain no double bonds between the carbon atoms and are therefore saturated

Question 3

What is a homologous series?

Answer 3

A family of molecules that all have the same general
formula and have chemical properties that are similar

Question 4

What is the general formula for alkanes?

Answer 4

CnH2n+2

Question 5

Give some examples of alkanes and their formulas

Answer 5

Methane | CH4
Ethane | C2H6
Propane | C3H8
Butane | C4H10

Question 6

What is fractional distillation used for?

Answer 6

It separates the fractions (parts of the mixture) of crude oil based on their chain lengths

Question 7

How does fractional distillation work?

Answer 7

-Crude oil is heated until it vaporises and then enters a tall fractionating column, which is hot at the bottom and gets cooler towards the top
-Vapours from the oil rise through the column
-Vapours condense when they become cool enough
-Liquids are led out of the column at different
heights

Question 8

What are the features of small hydrogen molecules?

Answer 8

Weak intermolecular forces, so they have low boiling points. They do not condense, but leave the column as gases

Question 9

What are the features of long hydrogen molecules?

Answer 9

Stronger intermolecular forces, so they have high boiling points. They leave the column as hot liquid bitumen

Question 10

What does hydrocarbon chain length affect?

Answer 10

The boiling point, viscosity, and flammability

Question 11

What is catalytic cracking?

Answer 11

Catalytic cracking needs a temperature of 550°C and a catalyst of aluminium oxide

Question 12

What is steam cracking?

Answer 12

Steam cracking uses a higher temperature of over 800°C and no catalyst

Question 13

What does cracking produce?

Answer 13

Alkenes

Question 14

Why is cracking important?

Answer 14

-It helps to match the supply of small fractions with the demand for them as fuels.
-Alkenes are used to produce polymers and as starting materials for the production of many other chemicals

Question 15

What is an alkene?

Answer 15

Alkenes are hydrocarbons with a double carbon-carbon
bond, C=C

Question 16

How do alkene properties differ to alkanes?

Answer 16

Alkenes are unsaturated and are more reactive than alkanes

Question 17

How do you test for alkenes?

Answer 17

They react with orange bromine water to turn it colourless.

Question 18

What is the general formula for alkenes?

Answer 18

CnH2n

Question 19

How do alkenes react?

Answer 19

Addition reactions with halogens, hydrogen or water

Question 20

Give some examples of alkenes and their formulas

Answer 20

Ethene | C2H4
Propene | C3H6
Butene | C4H8
Pentene | C5H10

Question 21

What is the general formula for an alkene and a halogen?
Give an example

Answer 21

alkene + halogen → halogenoalkane
ethene + chlorine → dichloroethane

Question 22

What is the general formula for an alkene and hydrogen?
Give an example

Answer 22

alkene + hydrogen → halogenoalkane
propene + hydrogen → propane

Question 23

What is the general formula for an alkene and hydrogen (hydrogenation)?
Give an example

Answer 23

alkene + hydrogen → alkane
propene + hydrogen → propane
(requires a catalyst)

Question 24

What is the general formula for an alkene and water (hydration)?
Give an example

Answer 24

alkene + water (steam) → alcohol
butene + water → butanol
(requires 300°C and a catalyst)

Question 25

What is the functional group of alcohol?

Answer 25

-OH

Question 26

Give some examples of alcohols and their formulas

Answer 26

Methanol | CH3OH Ethanol | C2H5OH Propanol | C3H7OH Butanol | C4H9OH

Question 27

How can ethanol be produced?

Answer 27

Fermentation (anaerobic respiration in yeast) glucose → ethanol + carbon dioxide

Question 28

What are the conditions needed for fermentation?

Answer 28

-sugars dissolved in water, and mixed with yeast -an air lock to allow carbon dioxide out, while stopping air getting in -warm temperature, 25-35°C

Question 29

What are alcohols used for?

Answer 29

-Methanol is used as a chemical feedstock. It’s toxic, so it’s added to industrial ethanol (methylated spirits) to prevent people from drinking it. -Ethanol is the alcohol present in alcoholic drinks. It is also used as a fuel and a solvent. -Propanol and butanol are also used as solvents and fuels

Question 30

What affects the solubility of alcohols?

Answer 30

When the alcohols with the shortest hydrocarbon chains are added to water, they mix easily to produce a solution. However, the solubility decreases as the length of the alcohol molecule gets longer, so butanol is less soluble than propanol. It may not mix easily, and two distinct layers might be left in the container

Question 31

How are alcohols oxidised?

Answer 31

Alcohols can be oxidised without combustion to produce carboxylic acids.

Question 32

What is the functional group of a carboxylic acid?

Answer 32

-COOH

Question 33

Give some examples of carboxylic acids and their formulas

Answer 33

Methanoic acid | HCOOH Ethanoic acid | CH3COOH Propanoic acid | C2H5COOH Butanoic acid | C3H7COOH

Question 34

What are the properties of carboxylic acids?

Answer 34

-dissolve in water to form acidic solutions with pH values less than 7 -react with metals to form a salt and hydrogen -react with bases to form a salt and water -react with carbonates to form a salt, water and carbon dioxide

Question 35

What is the general formula for the formation of esters?

Answer 35

alcohol + carboxylic acid → ester + water

Question 36

What is the functional group of esters?

Answer 36

-COO-

Question 37

What are the features of esters?

Answer 37

Esters have fruity smells and can be used as solvents

Question 38

What kind of acids are carboxylic acids?

Answer 38

Weak acids

Question 39

How does addition polymerisation work?

Answer 39

many small molecules (monomers) join together to form very large molecules (polymers)

Question 40

What is condensation polymerisation?

Answer 40

When these types of monomers react they join together, usually losing small molecules such as water, and so the reactions are called condensation reactions

Question 41

What are amino acids?

Answer 41

Molecules which have at least two functional groups

Question 42

Which functional groups do amino acids contain?

Answer 42

-NH2 and -COOH

Question 43

What are the results of polymerisation of amino acids?

Answer 43

polypeptides and proteins

Question 44

What is the simplest amino acid?

Answer 44

Glycerine

Question 45

What is DNA made from?

Answer 45

two polymer strands made from nucleotides

Question 46

What are proteins?

Answer 46

Biological polymers made inside cells

Question 47

What are starch and cellulose?

Answer 47

Biological polymers which are made by plants

Question 48

What are the monomers of starch and cellulose?

Answer 48

Sugar molecules

Question 49

What is starch?

Answer 49

Starch is used by plants as a way of storing energy as a complex carbohydrate

Question 50

What is cellulose?

Answer 50

Cellulose is used to make the strong cell wall which gives plant cells (and therefore plants) strength