C2 Salts and electrolysis

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  • Created by: KAustria
  • Created on: 10-05-14 09:41
What to acids produce when added to water?
H + Hydrogen ions
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What is formed when we disolve a substance in water?
Aqueous soltutions
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What do bases do to acids
Bases react with acids and neutralise
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What are alkalis?
Bases that dissolve in water to make alkaline solutions.
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What do Alkali's produce when dissolved in water?
Hydroxide ions, OH -
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What metals react with acids what do they produce?
A Salt and Hydrogen. Metal + Acid ---> Salt + Hydrogen
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What are metal hydroxides and metal oxides?
Bases
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When an acid reacts with a base, what is produced?
A Salts and Water. Acid + Base ---> A salt + Water
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How can salts be made?
1. Adding a metal or case insoluble in water to acid untill it has been reacted 2. The mixture is filtered to removed excess reactant 3. Water is evapourated from the solution 4. It crystallises
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How are chloride mades?
From hydrochloric acid, nitrates from nitric acid and sulfates from sulfuric acid.
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what is formed when acids and alkalis react? What is the neutralisation equation?
A soluble salt + water. H+ + OH - --> H2O
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How is solid state obtained from a solution of alkali and acid?
Crystallisation
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What is a precipitate?
A solid formed when two substances react together. It can be filtered, washed and dried.
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What is electrolysis?
The process that uses electricity to break down ionic compounds into elements
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What is the substance that is broken down by electrolysis?
Electrolyte
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How do ions in electrolyte react to the placed charge rods?
Move to the electrodes where they are discharged to produce elements.
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What happens in the positive electrode?
Negatively charged ions are attracted to the positive electrode where they lose their electrons to form non-metallic elements.
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What happens in the negative electrode?
Positively charged ions are attracted where they form metals or hydrogen by gaining an electron
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What is the gaining of electrons also known as?
Reduction
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What is the loss of electrons also known as?
Oxidation
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How can you represent the changes at the electrodes?
By half equations
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Why aren't all ions reduced or oxidised?
Because the least reactive ions re the ones that are attracted tot he electrodes
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Why is aluminim oxide mixed with cryolitein the elctrolysis cell?
So that aluminium oxide can melt at 850° which is a lower temperature than if ti was melted on its own.
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What is the over reaction of aluminium oxide in electrolysis?
Aluminium oxide --> Aluminium + Oxygen 2 Al2O3(l) --> 4Al + 3 O2
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What happens to the aluminium that is produced?
It is taken away form the bottom of the cell
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What happens at the negative electrode in extraction of aluminium?
Aluminium ions are reduced to aluminium atoms by gaining electrons, and it collected from the bottom of the cell.
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What happens at the positive electrode in extraction of aluminium?
Oxide ions are oxidised to oxygen atoms by losing electrons and the oxygen atoms form oxygen molecules.
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Why is carbon dioxide produce in the extraction of aluminium?
Electrodes are made out of carbon so the oxygen reacts with the electordes to make carbon dioxide.
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What are the half equation for aluminium extraction?
Negative : Al+3 + 3e- ---> Al Positive: 2O-2 - 4e- ---> 2O2
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What is brine?
sodium chloride in water
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What are ions are present in sodium chloride solution?
H+ Na+ CH - OH-
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what are the uses of the products of electrolysis of brine?
1. Sodium hydroxide is used in soaps, bleach, paper 2. Chlorine is used a a disinfectant 3. Hydrogen is used to make margarine
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What is electroplating?
Using electrolysis to put a thing coating of metal onto an object.
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What are the 4 main reasons to why electroplating is done?
1. Make an object look attractive 2. Protect an object from corroding 3. increase hardness of a surface 4. Reduce costs instead of using pure metal
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In electroplating what is placed in the negative and positive electrodes?
Positive - Made form the plating of metal Negative - The object needed to be electroplated
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Other cards in this set

Card 2

Front

What is formed when we disolve a substance in water?

Back

Aqueous soltutions

Card 3

Front

What do bases do to acids

Back

Preview of the front of card 3

Card 4

Front

What are alkalis?

Back

Preview of the front of card 4

Card 5

Front

What do Alkali's produce when dissolved in water?

Back

Preview of the front of card 5
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