Organic chemistry pt 1 (Hydrocarbons - fermentation)

Question 1

What is crude oil? (3)

Answer 1

• a finite resource found in rocks
• the remains of ancient biomass consisting mainly of plankton that was buried in mud
• a mixture of very large hydrocarbons

Question 2

Most of the hydrocarbons in crude oil are ________

Answer 2

alkanes

Question 3

The larger the hydrocarbon: (4)

Answer 3

• the more viscous it is
• higher its boiling point
• less volatile it is
• less flammable

Question 4

the equation for the combustion of hydrocarbon

Answer 4

hydrogen + oxygen = carbon dioxide + water (+ energy)

Question 5

During the combustion of hydrocarbon, carbon and hydrogen are …….

Answer 5

oxidised

Question 6

The general formula for alkanes

Answer 6

CnH2n+2

Question 7

Alkanes are : (2)

Answer 7

• saturated compounds
• unreactive but burn well

Question 8

the first four alkanes

Answer 8

Methane, ethane, propane, butane

Mary Eats Pickled Beetroot

Question 9

Why is there a greater demand for shorter- chain alkanes and carbons as fuels?

Answer 9

because they release energy more quickly by burning

because they are easy to ignite and have low boiling points

Question 10

What does each fraction in fractional distillation contain?

Answer 10

hydrocarbon molecules with a similar number of carbon atoms

Question 11

What is the process of fractional distillation?

Answer 11

1) crude oil is heated until it evaporates
2) the vapour moves up the fractionating column

• longer hydrocarbons have high boiling points so they condense back into liquids near the bottom
• shorter hydrocarbons have low boiling points so they are near the top

3) end up with the crude oil mixture separated out into different fractions

Question 12

What can the fractions in fractional distillation be processed to produce?

Answer 12

fuels and feedstock for the petrochemical industry

Question 13

What fuels are produced in crude oil

Answer 13

petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases

Question 14

What is produced by the petrochemical industry?

Answer 14

solvents, lubricants, polymers, detergents

Question 15

What happens when combustion is not complete?

Answer 15

CO, unburnt fuels and solid particles containing soot may be released

Question 16

what is carbon monoxide?

Answer 16

a colourless, odourless, toxic gas

Question 17

How do particulates impact the environment?

Answer 17

cause global dimming by reducing the amount of sunlight reaching the Earth’s surface and cause damage to people’s lungs

Question 18

How is nitrogen oxide formed and what is the effect of it on people and the environment?

Answer 18

due to high temperatures when fuels burn, nitrogen in the air can react with oxygen to form nitrogen oxide these gases can cause respiratory problems in people and from acid rain. which damages plants and buildings

Question 19

What is cracking?

Answer 19

when longer-chain hydrocarbons are broken down into shorter useful hydrocarbons

Question 20

Shorter hydrocarbons are _________ reactive than Longer-chain hydrocarbons

Answer 20

more

Question 21

What is the process for catalytic cracking?

Answer 21

1) liquid long-chain hydrocarbons are soaked in ceramic wool so it won’t mix with the catalyst and are heated so they are vapourised
2) The vapour will then be passed over a hot powdered aluminium oxide or silicon dioxide
3) the long-chain molecules split apart on the surface of the specks of the catalyst

Question 22

What is the process for steam cracking?

Answer 22

1) vapourised hydrocarbons are mixed with steam
2) they are then heated at a high temperature

Question 23

What are the products of cracking long-chain alkanes?

Answer 23

short chain alkanes and alkenes.

Question 24

Features of Alkenes?

Answer 24

• unsaturated hydrocarbons as there is a carbon double bond
• more reactive than alkanes as more atoms can easily be added to the carbons at the double bond

Question 25

What are the first four alkenes

Answer 25

ethene, propene, butene, pentene

Question 26

What is the formula for combustion for alkenes and describe how they burn?

Answer 26

alkene + oxygen

=

carbon + carbon monoxide + carbon dioxide + water

they tend to burn with smokier flames than alkanes due to incomplete combustion

Question 27

What is an addition reaction?

Answer 27

when carbon- carbon double bond opens up to leave a single bond and a new atom is added to each carbon

Question 28

What are the different types of addition reactions for alkenes?

Answer 28

• reaction with steam (hydration)
• reaction with bromine and ethene
• hydrogenation
• reaction with halogens

Question 29

What is hydrogenation and what is needed in it?

Answer 29

the addition of hydrogen to an alkene which produces an alkane

• nickel catalyst
• a temperature of 150 degrees is needed

Question 30

What happens when halogens react with alkenes?

Answer 30

the molecules formed become saturated with the carbon double bond each becoming bonded to a halogen atom

Question 31

what is the product of bromine and ethene?

name the chemical formula and draw it

what time of reaction is this

Answer 31

dibromoethane

C₂H₄Br₂

addition reaction

Question 32

How do you test for alkenes?

Answer 32

when bromine water is added to an alkane, no reaction will happen and it’ll stay bright orange

when added to an alkene it will turn colourless

Question 33

What are alcohols?

Answer 33

carbon-based molecules that contain the functional group, hydroxyl,

-OH

Question 34

What is the first four alcohols in the homologous series: hydroxyl

Answer 34

Methanol, Ethanol, Propanol, Butanol

Question 35

What is the General formula for alcohols?

Answer 35

C_nH_2n+1OH

Question 36

What are the features for alcohols?

** what happens to alcohol in water

what happens when it reacts with sodium

what do alcohols produce during combustion

what are they used as

what happens when they react with oxidising agents?

Answer 36

• dissolve in water to form neutral solutions
• react with sodium to produce hydrogen
• burn in air to produce carbon dioxide + water
• are used as fuels and solvents
• they react with oxidising agents to form carboxylic acids and water

Question 37

What is fermentation?

Answer 37

a chemical reaction in which ethanol and carbon dioxide are produced from glucose mixed with yeast

Question 38

what is the equation for fermentation?

Answer 38

sugar —–> ethanol + CO₂

Question 39

What is the optimum conditions for fermentation to work at?

Answer 39

37 degrees ( warm temperature

slightly acidic solutions

under anaerobic conditions

yeast

Question 40

What happens if the temperatures are too high or too low during fermentation?

Answer 40

too low: the yeast becomes inactive and the rate of reaction slows

too high: the yeat is denatured and stops working

Question 41

Advantages and disadvantages to fermentation?

Answer 41

Pros :

• low temp = less energy
• glucose is from plant = renewable

Cons :

• ethanol produced is in an aqueous solution = purified by distillation = high energy

Question 42

Pros and cons of making ethanol with hydrogenation

Answer 42

pros :

• high yield

cons :

• high temperature = more energy

Question 43

What is the product of hyrdogenation?

Describe

Answer 43

double double carbon bond in the alkene becomes single and two hydrogen atoms are added onto the ends

an alkane is made

Question 44

What is hydration?

What are the conditions and productions?

Answer 44

reacting alkene with water = addition reaction

Ethene + water (must be steam) —> ethanol

300 degrees celsius and 70 atms

phosphoric acid as catalyst