Chemistry- Electricity and chemical change

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  • Created by: Kitsune
  • Created on: 04-07-16 05:11
What is electricity?
A stream of electrons
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What are insulators?
Substances that don't conduct electricity as they don't have free electrons
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Which substances conduct?
Metas and graphite, ionic substances when dissolved or molten
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What is electrolysis?
The breakdown of an ionic compound, molten or in an aq. solution, by the passage of electricity
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What is electrolyte?
A solution that conducts electricity
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Describe the electrolysis of molten lead bromide
At cathode lead ions gain electron and lead forms below cathode. At anode bromide ions lose electrons and bromine gas bubbles off.
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What can inert electrodes be made out of?
Carbon, platinum, graphite
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Which electrode carries which charge?
Positive anode, negative cathode
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What are the rules of electrolysis of molten ionic compounds?
Metal at cathode, non metal at anode
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What forms at cathode in an aqueous solution?
Metal or hydrogen
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Why can hydrogen form at cathode instead of a metal?
Because if a metal is more reactive than hydrogen it will want to stay as an ion
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Why are the products different in electrolysis of molten or dissolved compounds?
In an aq. solution there are ions of water that take part in electrolysis
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What forms at anode in an aqueous solution?
A non-metal or oxygen
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When does oxygen form at anode instead of a non metal?
When the solution is dilute
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At cathode, ions ... electrons
gain
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At anode, ions ... electrons
lose
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What is brine?
A concentrated solution of sodium chloride, or common salt
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What is the word equation for electrolysis of brine?
Sodium chloride + water = chlorine + hydrogen + sodium hydroxide
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During the electrolysis of brine, what forms at the cathode?
Hydrogen gas
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During the electrolysis of brine, what forms at the anode?
Chlorine gas
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What separates the gases formed during electrolysis of brine?
The partially permeable membrane
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What takes place at cathode?
Reduction
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What takes place at anode?
Oxidation
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What are the products of electrolysis of brine?
Chlorine, hydrogen, sodium hydroxide
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How are the products of electrolysis of brine dangerous?
Chlorine- poisonous, hydrogen- flammable, sodium hydroxide- corrosive
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What are the uses of chlorine?
Medical drugs, paints, bleaches
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What are the uses of hydrogen?
Hydrogen peroxide, hydrogen fuel cells, making nylon
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What are the uses of sodium hydroxide?
Medical drugs, paper, soap
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What are the other 2 uses of electrolysis?
Refining and electroplating
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Describe how copper is refined
The electrolyte is dilute copper sulphate solution, copper on anode dissolves, impurities drop to the floor as sludge, a layer of pure copper builds up at cathode
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Why do we want copper as pure as possible?
The purer the better it conducts electricity
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Define electroplating
Coating a metal with another metal to make it look better or prevent corrosion
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Describe electroplating
At cathode place the object to be electroplated, at anode place metal x, the electrolyte is a soluble solution of a compound of metal x
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What are the uses of electroplating?
Steel car bumpers coated with chromium, steel cans coated with tin, metal jewellery coated with silver
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Other cards in this set

Card 2

Front

What are insulators?

Back

Substances that don't conduct electricity as they don't have free electrons

Card 3

Front

Which substances conduct?

Back

Preview of the front of card 3

Card 4

Front

What is electrolysis?

Back

Preview of the front of card 4

Card 5

Front

What is electrolyte?

Back

Preview of the front of card 5
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