C5

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  • Created by: Emily
  • Created on: 07-06-13 16:21
what is electrolysis?
it's a chemical reaction in which an ionic liquid is broken down into it's elements using an electric current
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what happens to the ions in elecrolysis?
ionic solid are fixed and can't move and an ionic substance that is molten or in solution is free to move
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what are the positive and negative ions called?
pos- cations discharge at the negative electrode (cathode) neg- anions discharge at the pos electrode (anode)
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when is more substance made?
if a larger current flows or the current flows for a longer time
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what two factors affect the amount of substance being made during electrolysis?
temperature and pressure
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what kind of reaction is between hydrogen and oxygen?
exothermic, as it releases energy
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what happens when hydrogen reacts exothermicly with oxygen in a fuel cell?
it makes an electric current
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what are the advantages and disadvantages of using a fuel cell?
A- produce less pollution, efficient, simple to construct and are lightweight and compact D- contain poisonous catalysts and it needs energy which may come from burning of fossil fuels
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what kind of reaction is rusting?
redox reaction, this involves both oxidation and reduction
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what does oxidation involve?
the loss of electrons
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why is rusting a redox reaction?
iron loses electrons and oxygen gains electrons
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how can you prevent/protect iron and steel from rusting?
galvanising, alloying, sacrificial protection and tin plating
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what is a displacement reaction?
when a more reactive metal displaces a less reactive metal in a reaction
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what are alcohols?
a family of organic compounds containing hydrogen, carbon and oxygen
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what are some used of ethanol?
to make alcoholic drinks, to make solvents and fuel for cars
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how can ethanol be made?
by fermentation
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how can ethanol be extracted from the fermentation mixture?
by fractional distillation
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why does the fermentation temp have to be kept between the optimum temp of 25-50c?
if it falls below the yeast become inactive and if it rises the enzymes denature and stop working
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is fermenting and hydration a batch or continuous process?
fermenting is a batch process and hydration is a continuous process
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why is ethanol made by hydration non-renewable?
because the ethene will have been made by cracking components of crude oil
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advantages and disadvantages of fermentation and hydration..
fermentation is slow and the ethanol has to be purified- uses a lot of energy and is expensive and it has a high percentage yield, hydration has a 100% atom economy and is fast
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what are CFC's and what were they used for?
they are chlorine, fluorine and carbon, they were used as refrigerants and in aerosols because they have a low boiling point, insoluble and unreactive
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what is now used as a safer alternative to CFC's?
hydrocarbons (alkanes) or hydro-fluorocarbons (HFC's)
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what does harmful UV light cause?
increased aging of skin and risk of sunburn, skin cancers and increased risk of cataracts
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what happens when a CFC molecule is it by UV light?
a chlorine atom called a radical is produced
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what does soft and hard water do?
soft- water lathers well with soap hard- doesn't lather with soap
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what is the hardness of water caused by?
calcium and dissolved salts
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what is temporary and permanent harness of water?
permanent- dissolved substances like calcium sulfate- can't be destroyed by boiling, temp- forms when rainwater comes into contact with rock that contains calcium carbonate- can be removed by boiling
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what is limescale?
insoluble calcium carbonate
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how can you remove the hardness of water?
adding washing soda or passing the water through an ion-exchange column
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what kind of bonds are saturated and un sat?
un sat- double sat- single
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what happens when you shake an oil/fat with bromine water to test if it's sat or un sat?
fat is un sat it will change from orange to colourless, if sat it will remain orange
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what is saponification?
the process used to make soap by reacting vegetable oil with hot sodium hydroxide
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what does an active detergent, bleach, optical brighter and enzymes do?
AD- does cleaning B- removes coloured stains OB- makes whites appear brighter E- break up food and protein stains in low temp wahses
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is water the solute or solution and what about washing powder?
water is the solvent and the washing powder is the solute because it's soluble
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what are the intermolecular molecules like making up a stain?
they are weak
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what does washing up liquid contain?
an active detergent, water, water softener, rinse agent and colour and fragrance
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what kind of head and tail does a detergent molecule have?
it has a hydrophilic head and a hydrophobic tail
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Other cards in this set

Card 2

Front

what happens to the ions in elecrolysis?

Back

ionic solid are fixed and can't move and an ionic substance that is molten or in solution is free to move

Card 3

Front

what are the positive and negative ions called?

Back

Preview of the front of card 3

Card 4

Front

when is more substance made?

Back

Preview of the front of card 4

Card 5

Front

what two factors affect the amount of substance being made during electrolysis?

Back

Preview of the front of card 5
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