Organic chemistry pt 1 (Hydrocarbons - fermentation) Flashcards Preview

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Flashcards in Organic chemistry pt 1 (Hydrocarbons - fermentation) Deck (44)
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1
Q

What is crude oil? (3)

A
  • 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
2
Q

Most of the hydrocarbons in crude oil are ________

A

alkanes

3
Q

The larger the hydrocarbon: (4)

A
  • the more viscous it is
  • higher its boiling point
  • less volatile it is
  • less flammable
4
Q

the equation for the combustion of hydrocarbon

A

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

5
Q

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

A

oxidised

6
Q

The general formula for alkanes

A

CnH2n+2

7
Q

Alkanes are : (2)

A
  • saturated compounds
  • unreactive but burn well
8
Q

the first four alkanes

A

Methane, ethane, propane, butane

Mary Eats Pickled Beetroot

9
Q

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

A

because they release energy more quickly by burning

because they are easy to ignite and have low boiling points

10
Q

What does each fraction in fractional distillation contain?

A

hydrocarbon molecules with a similar number of carbon atoms

11
Q

What is the process of fractional distillation?

A

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

12
Q

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

A

fuels and feedstock for the petrochemical industry

13
Q

What fuels are produced in crude oil

A

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

14
Q

What is produced by the petrochemical industry?

A

solvents, lubricants, polymers, detergents

15
Q

What happens when combustion is not complete?

A

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

16
Q

what is carbon monoxide?

A

a colourless, odourless, toxic gas

17
Q

How do particulates impact the environment?

A

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

18
Q

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

A

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

19
Q

What is cracking?

A

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

20
Q

Shorter hydrocarbons are _________ reactive than Longer-chain hydrocarbons

A

more

21
Q

What is the process for catalytic cracking?

A

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

22
Q

What is the process for steam cracking?

A

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

23
Q

What are the products of cracking long-chain alkanes?

A

short chain alkanes and alkenes.

24
Q

Features of Alkenes?

A
  • 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
25
Q

What are the first four alkenes

A

ethene, propene, butene, pentene

26
Q

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

A

alkene + oxygen

=

carbon + carbon monoxide + carbon dioxide + water

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

27
Q

What is an addition reaction?

A

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

28
Q

What are the different types of addition reactions for alkenes?

A
  • reaction with steam (hydration)
  • reaction with bromine and ethene
  • hydrogenation
  • reaction with halogens
29
Q

What is hydrogenation and what is needed in it?

A

the addition of hydrogen to an alkene which produces an alkane

  • nickel catalyst
  • a temperature of 150 degrees is needed
30
Q

What happens when halogens react with alkenes?

A

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

31
Q

what is the product of bromine and ethene?

name the chemical formula and draw it

what time of reaction is this

A

dibromoethane

C2H4Br2

addition reaction

32
Q

How do you test for alkenes?

A

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

33
Q

What are alcohols?

A

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

-OH

34
Q

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

A

Methanol, Ethanol, Propanol, Butanol

35
Q

What is the General formula for alcohols?

A

CnH2n+1OH

36
Q

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?

A
  • 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
37
Q

What is fermentation?

A

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

38
Q

what is the equation for fermentation?

A

sugar —–> ethanol + CO2

39
Q

What is the optimum conditions for fermentation to work at?

A

37 degrees ( warm temperature

slightly acidic solutions

under anaerobic conditions

yeast

40
Q

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

A

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

too high: the yeat is denatured and stops working

41
Q

Advantages and disadvantages to fermentation?

A

Pros :

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

Cons :

  • ethanol produced is in an aqueous solution = purified by distillation = high energy
42
Q

Pros and cons of making ethanol with hydrogenation

A

pros :

  • high yield

cons :

  • high temperature = more energy
43
Q

What is the product of hyrdogenation?

Describe

A

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

an alkane is made

44
Q

What is hydration?

What are the conditions and productions?

A

reacting alkene with water = addition reaction

Ethene + water (must be steam) —> ethanol

300 degrees celsius and 70 atms

phosphoric acid as catalyst