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Chemistry GCSE > Paper 1 GCSE > Flashcards

Paper 1 GCSE Flashcards

(68 cards)

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1
Q

why can’t you use the lab method of making ammonia in industry

A

it is impractical to use a steam bath and burette for large quantities and using crystallisation to get solid ammonium sulphate is too slow

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2
Q

how do you make ammonium sulphate in industry

A

ammonia is made using the Haber process and
sulphuric acid is produced using the contact

one industrial method uses a large reaction chamber filled with ammonia gas and sulphuric acid is sprayed into the reaction chamber where it reacts with ammonia to produce ammonium sulphate powder which falls to the bottom of the chamber

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3
Q

what is atom economy

A

the atom economy of a reaction tells you what percentage of the mass of the reactants has been converted into your desired product when manufacturing a chemical

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4
Q

what is the atom economy equation

A

total mr of desired product over total mr of all products times by 100

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5
Q

discuss why a high atom economy is better for profits and for the environment

A
  • reactions with a low atom economy use up resources very quickly and make lots of waste products that have to be disposed of which tends to make reactions unsustainable
  • low atom economy reactions aren’t profitable as raw materials can be expensive to buy and waste products expensive to remove and dispose of responsibly
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6
Q

how can we improve atom economy

A
  • find a use for the waste products

- come up with a reaction that has useful by-products because there is normally multiple ways to make what you want

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7
Q

what things must you consider in industry

A
  • atom economy
  • percentage yield
  • rate of reaction
  • reversible reaction
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8
Q

how do you work out percentage yield

A

percentage yield = actual yield over theoretical yield times by 100

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9
Q

what is percentage yield

A

the amount of products you get out of what you used

the more reactants you use the higher the actual yield would be but the percentage yield doesn’t depend on the amount of reactants
the theoretical yield is the mass of product you’d make if all the reactants were converted to products

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10
Q

why do you never get 100% yield

A

incomplete reactions - if not all the reactants are converted into products the reaction is incomplete

practical losses - you lose a bit when you transfer chemicals between containers as some is left on the container walls

unwanted reactions - if unexpected reactions happen the yield of the intended product goes down. These can be caused by impurities in the reactants or sometimes by changes to the reaction conditions

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11
Q

what is the concentration equation

A

concentration = moles or mass divided by volume of solution

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12
Q

what is corrosion

A

gain of oxygen / rusting

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13
Q

what is the rusting of iron

A

a redox reaction

  • metals corrode in the presence of oxygen and water to form their metal oxides
  • corrosion of metals is caused by redox reactions. The metal loses electrons so is oxidised but simultaneously oxygen gains electrons when it reacts with the metal
  • rusting is the name for the corrosion of iron
  • rusting only happens when the iron is in contact with both oxygen from the air and water
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14
Q

discuss the experiment to show iron needs both water and air to rust

A

three boiling tubes:

1st - put iron nail in with just water it won’t rust. Boil the water beforehand to remove oxygen and put a layer of oil on top of the water to stop air getting in

2nd - if you put an iron nail in a boiling tube with just air it won’t rust. Calcium chloride can be used to absorb any water from the air

3rd - if you put an iron nail in a boiling tube with air and water it will rust

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15
Q

what different ways can you prevent rusting

A
  • coat iron with a barrier to keep out water, oxygen or both
  • painting is ideal for large and small structures and can also be nice and colourful
  • oiling and greasing has to be used when moving parts are involved like bike chains
  • using sacrificial protection (placing a more reactive metal with the iron so the water and oxygen react with this sacrificial metal instead of the object you’re protecting)
  • galvanising
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16
Q

what is galvanising

A

an example of sacrificial protection where a coat of zinc is put onto an iron object to prevent rusting. The zinc acts as sacrificial protection as its more reactive than iron so it will lose electrons and corrode in preference to iron. The zinc also acts as a barrier.

steel buckets and corrugated iron roofing are often galvanised

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17
Q

what is electroplating

A

coating the surface of a metal with another metal using electrolysis
the cathode is the object your going to electroplate and the anode is the bar of metal your using for the plating
your electrolyte is a solution containing the metal ions of the metal your plating

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18
Q

why is electroplating useful

A
  • household objects like cutlery and cooking utensils are electroplated with metals to stop them corroding
  • the metals used for protection are unreactive and don’t corrode easily
  • jewellery and decorative items are often electroplated with metals like gold and silver because it improves appearance making them look shiny and attractive
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19
Q

how is steel made and why is it better than pure iron

A

steel is made by adding small amounts of carbon to the pure iron

  • steel is harder than iron
  • stronger than iron as long as carbon isn’t greater than 1%
  • iron on its own will corrode fairly quickly
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20
Q

what are the properties of transition metals

A
  • hard, strong, shiny, malleable
  • conduct heat and electricity well
  • high melting points
  • high densities
  • compounds of transition metals are very colourful
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21
Q

why are the properties of transition metals gold and copper good for their purposes

A

gold:

  • used in jewellery because it is shiny and malleable
  • also a good electrical conductor and corrosion resistant so is used in some electrical components

copper:

  • used for water pipes
  • because malleable and corrosion resistant
  • another good electrical conductor so is used a lot in electrical wiring
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22
Q

what does a catalyst do

A

lowers the activation energy to speed up the rate of reaction without changing the amount of products or reactants

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23
Q

how do you get the hydrogen and nitrogen for the Haber process

A
  • nitrogen in the air is about 78% so it can be obtained from their through fractional distillation after the air has been cooled
  • hydrogen can be extracted from hydrocarbons from source such as natural gas or crude oil
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24
Q

when can equilibrium only be reached

A

if the equation is taking place in a closed system

when a reaction is at equilibrium it doesn’t mean the amount of products and reactants are equal

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25
what is a life cycle assessment
a life cycle assessment or LCA looks at each stage of the life of a product - making the material from natural raw materials - to making the product from the material - using the product - disposing of the product it works out the potential environmental impact of each stage
26
discuss the choice of material stage of life cycle assessments
- metals have to be mined and extracted from their ores and these processes need a lot of energy and cause a lot of pollution - raw materials for chemical manufacture often come from crude oil which is a non-renewable resource and is decreasing. - Also obtaining crude oil from the ground and refining it into useful raw materials requires a lot of energy and generates pollution
27
discuss the manufacture stage of life cycle assessments
- manufacturing products uses a lot of energy and other resources - it can also cause a lot of pollution e.g. harmful fumes like HCl or CO - you also need to think about waste products and how to dispose of them - some waste can be recycled and turned into other useful chemicals reducing the amount that ends up polluting the environment - most chemical manufacture needs water and business have to make sure they don't put the polluted water back into the environment at the end of the process
28
discuss the product use stage of the life cycle assessments
- using the product can also damage the environment - paint gives off toxic fumes - burning fuels releases greenhouse gases and other harmful substances - fertilisers can leach into streams and rivers causing damage to ecosystems
29
discuss the disposal stage of life cycle assessments
- products are often disposed of in a landfill site at the end of their life - this takes up space and can pollute land and water - products might be incinerated (burnt) which causes pollution
30
``` other than - CO2 emissions - waste solid produced - water used - expected lifespan of product what other things should be considered when performing a life cycle assessment for the car ```
- energy required to extract the raw materials - whether the raw materials are renewable or not - whether other harmful emissions are produced - whether waste products are harmful or not - how environmentally friendly the cars are to dispose of
31
discuss bioleaching as a method of extracting metals from their ore
uses bacteria to separate metals from their ores the bacteria get energy from the bonds between the atoms in the ore separating the metal from the ore in the process the leachate (the solution produced by the process) contains metal ions which can be extracted by electrolysis or displacement with a more reactive metals doesn't require large amounts of energy so it is cheaper but produces toxic substances like sulphur dioxide which can cause acid rain and damage the environment
32
what is phytoextraction
this involves growing plants in soil that contains metal compounds the plants can't use or get rid of the metals so they build up in the leaves these plants can be harvested, dried and burned in a furnace the ash contains metal compounds from which the metal can be extracted by electrolysis or displacement reactions - increases potential copper reserves - you don't need a lot of energy so it is cheaper - enables extraction of low grade ores - you have to wait for the plant to grow so it takes a long time - only removes copper from the top layer of the soil - burn then uses electrolysis both of which need energy so it is still expensive to some extent
33
discuss electrolysis as more expensive than reduction with carbon
- you need electricity which is expensive - coats associated with melting or dissolving the metal ore so it can conduct electricity - reduction with carbon is far cheaper because the carbon is cheap and also acts a fuel to provide the heat need for the reaction to happen - metals lower down reactivity series cheaper to extract
34
discuss extracting aluminium from its ore
- extracted using carbon electrodes - aluminium oxide has a high melting point so is first dissolved in molten cryolite (an aluminium compound with a lower melting point than aluminium oxide) - this lowers the melting point - the ions in this molten mixture are free to move - during the electrolysis aluminium is formed at the cathode Al3+ + 3e- -> Al - oxygen forms at the anode anode 2O2- -> O2 + 4e- the overall equation is 2Al20 -> 4Al + 3O2
35
what are displacement reactions an example of
redox reactions in displacement reactions, a more reactive element reacts to take the place of a less reactive element in a compound. In metal displacement reactions, the more reactive metal loses electrons and the less reactive metal gains electrons. so during a displacement reaction the more reactive metal is oxidised and the less reactive metals reduced and this happens at the same rate making it a redox reaction.
36
how can you show some metals are more reactive than others
the more easily a metal atom loses its outer electrons and forms a positive ion, the more reactive it will be - put little piece of various metals into 20ml of dilute hydrochloric acid - make sure the pieces of metals are the same size and shape so you can compare the results. - the more reactive the metal is the faster the reaction with the acid will be - more reactive will fizz vigorously and less reactive metals will bubble a bit while unreactive metals won't react at all - show hydrogen is forming using squeaky pop an the louder the pop the more hydrogen has been made in the same time period and the more reactive the metal is - speed of reaction also indicated by rate at which bubbles of hydrogen gas are given off
37
will powdered metals react more quickly than lumps of metals
yes because they have a larger surface area
38
metal + water
metal hydroxide + hydrogen
39
discuss combustion
involves oxidation always exothermic CH4 + 2O2 -> CO2 + 2H2O - both the carbon and hydrogen are oxidised - they gain oxygen - the oxygen molecules are reduced as the oxygen atoms get split up by the reaction
40
why are the metals at the top of the reactivity series the most reactive
because they easily lose their electrons to form cations (positive ions) they are also oxidised and corrode very easily
41
why are the metals at the bottom of the reactivity series the least reactive
they don't give up their electrons to form cations as easily they are more resistant to oxidation
42
what is a base
a substance that reacts with an acid to produce a salt and water
43
what is an alkali
a base that is soluble in water all alkalis have a pH of more than 7 and they form OH- ions (hydroxide ions) in water the higher the concentration of hydroxide ions the higher the pH
44
in an acid the higher the concentration of hydrogen ions.....
the lower the pH
45
what colour is litmus in different things
red - acid purple neutral blue - alkaline
46
what colour is methyl orange in different things
red - acidic | yellow - neutral and alkaline
47
what colour is phenolphthalein
colourless in acid and neutral | pink - alkaline
48
what is the reaction between an acid and a base called
- neutralisation - it produces a salt and water - neutralisation reactions in aqueous solutions can also be shown as an ionic equation in terms of H+ and OH- ions - when an acid neutralises a base or vice versa the products are neutral
49
what is the core practical for investigating the neutralisation reaction between calcium oxide (a base) and dilute hydrochloric acid
- measure out 20 ml of hydrochloric acid into conical flask - use a pipette and measuring cylinder to do so - measure out 5g of copper oxide using mass balance - add calcium oxide to HCL - wait for base to completely react then record the pH of the solution using either a pH probe or universal indicator paper using glass rod to spot samples of solution onto paper - repeat until all acid has reacted and you get unreacted calcium oxide sitting at the bottom of the flask - plot graph to see how pH changes with the mass of base added
50
strong acids....
dissociate the most to release H+ ions
51
the ionisation or dissociate of a weak acid is...….
a reversible reaction
52
what does acid strength tell you
what proportion of the acid molecules ionise in water
53
acid + metal oxide
salt + water
54
acid + metal hydroxide
salt + water
55
acid + metal
salt + hydrogen
56
acid + metal carbonate
salt + water + carbon dioxide
57
what is a salt
an ionic compound formed during a neutralisation reaction between an acid and a base
58
why does hydrogen make a squeaky pop
because it the hydrogen burning with the oxygen in the air to form water
59
how do you make a pure dry sample of an insoluble salt
- precipitation reaction - react two soluble salts - e.g. to make lead chloride mix lead nitrate and sodium chloride 1) add one spatula of lead nitrate to a teat tube and add 20ml of water to dissolve it (use deionised water to make sure there are no other ions about 2) shake thoroughly to ensure all lead nitrate has dissolved 3) repeat with one spatula of sodium chloride 4) tip the two solutions into a small beaker and stir, the lead chloride should precipitate out 5) put a folded piece of filter paper into a filter funnel and place in conical flask 6) pour contents of beaker into filter paper and make sure the solution doesn't go above the filter paper in case some solid dribbles down the side 7) swill out the beaker with more deionised water and tip this into the filter paper to make sure you get all the precipitate 8) rinse contents of filter paper with deionised water to make sure all soluble sodium nitrate has been washed away 9) scrape lead chloride onto fresh filter paper and leave it to dry in an oven or desiccator
60
how do you make a soluble salt using an acid and an insoluble base
copper oxide in excess to sulphuric acid filter heat gently with Bunsen burner
61
how do you make a soluble salt using an acid/alkali reactions
titration :)
62
what do you do if your electrolyte is a solid ionic substance
you put it in a crucible and heat with Bunsen till its molten
63
what are the rules of the electrodes of an aqueous substance in electrolysis
you have H+ ions and OH- ions as well as the two ions of the electrolyte cathode - hydrogen gas produced if the metal is more reactive than hydrogen anode - if halide present that will be discharged and if not oxygen will be discharged 4OH- -> O2 + 2H20 + 4e-
64
discuss the electrolysis of copper sulphate with inert electrodes
cathode: copper is less reactive than hydrogen so is produced at cathode reduction Cu2+ + 2e- -> Cu anode: there aren't any halides present so oxygen an water are produced at the anode oxidization 4OH- -> O2 + 2H2O + 4e-
65
mass =
moles x mr
66
how do you calculate the amount of product from the limiting reactant
- write out balanced equation - work out relative formula masses (Mr) of the reactant and product you're interested in - find out how many moles there are of the substance you know the mass of - use balanced equation to work out how many moles there'll be of the other substance - use moles to calculate mass
67
discuss treatment of water in treatment plans
filtration - a wire mesh screens out twigs etc and then gravel and sand beds filter out any other solid bits sedimentation - iron sulphate or ammonium sulphate is added to the water which makes fine particles clump together and settle at the bottom chlorination - chlorine gas is bubbles through to kill harmful bacteria and other microbes
68
describe the structure of a metal
- lattice structure - regular arrangement - layers slide over each other making it malleable - positive ions in a sea of delocalised electrons - the electrons in the outer shell of the metal atoms are delocalised electrons allow charge to flow

Chemistry GCSE (2 decks)

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