C2 Chapter 5 Electrolysis

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What are ionic compounds?
Compounds that contain ions (charged ions)
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What charge do metal ions often carry?
Positive
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Why are ionic solids not able to conduct electricity?
Ions=locked in place by bonds->Cannot move->NoConduction
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How do we make ionic compounds conduct?
When melted or dissolved, ions can move. Therefore conduct.
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Describe what is meant by electrolysis.
Electric current through l/aq IC->It breaks down to its elements
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What is an electrolyte?
l/aq ionic compound that an electric current goes through
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What does OILRIG stand for?
Oxidation Is Loss, Reduction Is Gain
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How do we plate objects in metal?
Make the object the negative electrode. + attracted to -.
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The electrolyte needs to contain ions of a plating metal. Give an example of that electrolyte.
Copper sulfate solution.
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How do we extract the aluminium from its ore?
Smelt it at the high melting point of 2000oC
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Why is this expensive?
Because it uses a large amount of energy.
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How do we reduce the costs?
Al2O3 is dissolved in cryolite to lower the melting pt and energy
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What do the aluminium ions do at the negative electrode?
They gain 3 electrons forming aluminium metal (REDUCTION)
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What do the oxygen ions do at the positive electrode?
They lose 2 electrons forming oxygen gas.
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What are the electrodes made out of?
Carbon graphite
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What is therefore produced when the oxygen ions become oxygen gas?
Carbon dioxide because the oxygen reacts with the carbon.
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Why do the electrodes need top be changed regularly?
The carbon graphite electrode reacts with the oxygen gas.
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Give the half equation of aluminium at the negative electrode.
Al3+ + 3e- --> Al (REDUCTION)
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Give the half equation of oxygen at the positive electrode.
2O2- --> O2 + 4e- (OXYDATION)
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Why is 2 oxygen ions written?
Oxygen is a diatomic particle. O2
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Why is it the ionic compound is dissolved in solution?
We have to take into account the ions in water.
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Give an example of why.
H+ and Na+ are both +ve. We have to decide which one.
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How do we decide which one is attracted to the electrode?
The hydrogen is attracted if it's less reactive than the metal.
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In NaCl, is hydrogen or sodium attracted to the negative electrode?
Hydrogen.
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At the positive electrode which type of ions are attracted?
Halide ions and not the hydroxide OH- ion.
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In NaCl, is the chloride or the hydroxide ion attracted to the positive electrode.
Chloride
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What is chlorine gas used for?
Plastics and bleach.
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What is left in the solution after electrolysis?
Na+ and OH-. Therefore meaning sodium hydroxide solution.
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What is sodium hydroxide used for?
To make soap.
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Give the half equation at the negative electrode.
2H+ + 2e- --> H2 (REDUCTION)
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Give the half equation at the positive electrode.
2CL- - 2e- --> Cl2 2CL- --> CL2 + 2e-
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Other cards in this set

Card 2

Front

What charge do metal ions often carry?

Back

Positive

Card 3

Front

Why are ionic solids not able to conduct electricity?

Back

Preview of the front of card 3

Card 4

Front

How do we make ionic compounds conduct?

Back

Preview of the front of card 4

Card 5

Front

Describe what is meant by electrolysis.

Back

Preview of the front of card 5
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