Flashcards in Paper 1 GCSE Deck (68)
Loading flashcards...
1
why can't you use the lab method of making ammonia in industry
it is impractical to use a steam bath and burette for large quantities and using crystallisation to get solid ammonium sulphate is too slow
2
how do you make ammonium sulphate in industry
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
3
what is atom economy
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
4
what is the atom economy equation
total mr of desired product over total mr of all products times by 100
5
discuss why a high atom economy is better for profits and for the environment
- 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
6
how can we improve atom economy
- 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
7
what things must you consider in industry
- atom economy
- percentage yield
- rate of reaction
- reversible reaction
8
how do you work out percentage yield
percentage yield = actual yield over theoretical yield times by 100
9
what is percentage yield
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
10
why do you never get 100% yield
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
11
what is the concentration equation
concentration = moles or mass divided by volume of solution
12
what is corrosion
gain of oxygen / rusting
13
what is the rusting of iron
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
14
discuss the experiment to show iron needs both water and air to rust
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
15
what different ways can you prevent rusting
- 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
16
what is galvanising
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
17
what is electroplating
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
18
why is electroplating useful
- 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
19
how is steel made and why is it better than pure iron
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
20
what are the properties of transition metals
- hard, strong, shiny, malleable
- conduct heat and electricity well
- high melting points
- high densities
- compounds of transition metals are very colourful
21
why are the properties of transition metals gold and copper good for their purposes
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
22
what does a catalyst do
lowers the activation energy to speed up the rate of reaction without changing the amount of products or reactants
23
how do you get the hydrogen and nitrogen for the Haber process
- 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
24
when can equilibrium only be reached
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
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
