Organic Chemistry

Question 1

How does yeast produce alcohol

Answer 1

It uses sugar in anaerobic respiration for energy to produce ethanol and carbon dioxide. Conditions must be warm to make it fast and have oxygen to make sure aerobic respiration doesn’t occur.
Sugar—>ethanol + carbon dioxide
C6H12O6(aq) —> 2(C2H45OH) + 2(CO2)

Question 2

Benefits of alcohol

Answer 2

Less self conscious and more talkative

Question 3

Negatives of alcohol (short term)

Answer 3

Slower reaction times
Voilent or aggressive behaviour
Loss of balance and coordination
Vomiting and fainting
Dehydration, leading to hangover

Question 4

Long term effects of alcohol

Answer 4

Increased chance of heart disease and strokes
Liver cirrhosis, stops it working properly
Burnt oesophagus from all the vomiting

Question 5

Why can’t yeast make any drink over 15% alcohol

Answer 5

The yeast is killed by the alcohol once it reaches 15% which stops fermentation

Question 6

How can stronger drinks like spirits be made

Answer 6

It needs to be distilled. Heat up the weaker drink to boil the ethanol, then condense the ethanol and collect it in another beaker, this liquid will have a higher percentage of
Ethanol. Fractional distillation

Question 7

Describe fractional distillation of alcoholic drink

Answer 7

Drink placed in beaker that is heated to evaporate the drink. The vapour rises through a fractionating column, the water condenses here and goes back to the beaker but the ethanol passes all the way through. Ethanol vapour then goes through a condenser tube to make it liquid, it then flows into another beaker

Question 8

How can ethanol be made from crude oil

Answer 8

Ethene either obtained from the oil or from when it is cracked can be reacted with steam in the presence of a catalyst, this hydrates it, adding one hydrogen and a hydroxide to it, making it ethanol
Ethene + steam —> ethanol
C2H4 + H20 —> C2H5OH

Question 9

How can ethene be made from ethanol

Answer 9

With a suitable catalyst, the hydration reaction can be reversed into a dehydration reaction
Ethanol —> ethene + steam

Question 10

Advantages of ethanol from crude oil and disadvantages

Answer 10

It is 100% pure unlike fermentation which is 15% and can be distilled to 95%

It comes from non renewable crude oil, so fermentation is better

Question 11

Where do the sugars for fermentation come from

Answer 11

From starch crops such as sugar can, sugar beet and wheat. Some groups such as grapes already have suitable sugars

Question 12

What is the properties of the alkene family

Answer 12

They have one double carbon bond and burn well. The longer the chain, the harder it is to burn

Question 13

What is the general rule for alkene family chemical formula

Answer 13

CnH(2n)

Question 14

What are the properties of the alkane family

Answer 14

They’re fully saturated hydrocarbons with no double bonds. They burn well and the longer then chain, the worse they burn

Question 15

General formula for alkanes

Answer 15

CnH(2n+2)

Question 16

What is a homologous series

Answer 16

A family of compounds with similar properties but different amounts of carbons in them

Question 17

Properties of the hydroxyl group

Answer 17

Same as alkanes but one of the hydrogens is replaced with an OH molecule. This makes it an alcohol. All alcohols burn well with a blue flame. They’re good fuels.

Question 18

General formula for hydroxyl group

Answer 18

CnH(2n+1)OH

Question 19

How is Ethanoic acid made

Answer 19

Ethanol is oxidised in an oxidation reaction. This replaces two of the hydrogens with a double bonded oxygen

Question 20

Properties of ethanoic acid

Answer 20

Tangy sharp taste
Acidic
Acts as a preservative as kills bacteria

Question 21

Properties of acids

Answer 21

Turn litmus paper and uni indicator red
React with some metals to form hydrogen
React with bases or carbonates to make water and metal salt

Question 22

Properties of carboxylic acids

Answer 22

Acids

Question 23

General formula for carboxylic acids

Answer 23

CnH(2n)O2

The carboxyl group is COOH

Question 24

What are esters used for

Answer 24

Perfume smells as there molecules escape into the air easily

Food flavourings such as pear drops

Question 25

How are esters made

Answer 25

Carboxylic acid + alcohol —> ester + water

Question 26

How is ethyl ethanoate made

Answer 26

Ethanocic acid + ethanol —> éthyl ethanoate + water

C2H4O2 + C2H5OH —->

Question 27

What is polyester

Answer 27

A long chain of ester molecules that form strands that can be woven into fibres or can be made into solid plastic

Question 28

What are fats and oils

Answer 28

They are big esters made of long chained carboxylic acids and alcohols

Question 29

General formula for making soaps

Answer 29

Concentrated alkali + oil/fat —> soap + glycerol

Question 30

What is the structure of a soap molecule

Answer 30

Like a tadpole, a hydrophilic head and a hydrophilic hydro carbon tail. The head has a negatively charged oxygen so it’s an anion

Question 31

How does soap remove grease from fabrics

Answer 31

Hydroponic tail sticks into the grease and gets under it, the hydrophilic head pulls it away and removes the grease

Question 32

How can an unsaturated oil become a saturated fat

Answer 32

By bubbling hydrogen through it in the presence of a metal catalyst such as nickel, this hydrates the double bond in the hydrocarbon making it saturated. This is catalytic hydration

Question 33

How is margarine made

Answer 33

By bubbling hydrogen through vegetable oils to hydrate the and turn the oils into fats