C6-Electrolysis-Including 14.4 And 15.1-2
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What is an anode?
the positive electrode in electrolysis
What is brine?
concentrated sodium chloride solution that can undergo electrolysis to produce chlorine gas, hydrogen gas, and sodium hydroxide solution
What is a cathode?
the negative electrode in electrolysis
What is an electrolyte?
a liquid, containing free-moving ions, which is broken down by electricity in the process of electrolysis
What is a half equation?
an equation that describes reduction or oxidation
What does inert mean?
unreactive
What are cations?
positive ions
What are anions?
negative ions
Where do cations move towards during electrolysis?
the cathode
Where do anions move towards during electrolysis?
the anode
What are the electrodes made out of?
carbon graphite because it is a conductor, but also unreactive and has a high melting point
What happens to the ions at the electrodes?
they are discharged and they form elements
What is electrolysis?
The decomposition of an ionic compound into its elements by electricity
Why can’t covalent substances be broken down by electrolysis?
For a substance to be broken down by electrolysis, it must contain ions as they have a charge. Covalent substances do not contain charged ions, only neutral atoms
What type of reaction happens at the anode and why?
Oxidation, this is because the negative ions lose electrons to the positive anode
What type of reaction happens at the cathode and why?
Reduction, Positive ions gain electrons from the negative cathode
Describe the movement of electrons during electrolysis
Electrons move from the positive anode towards the negative electrode through the circuit
What is the -ve electrode?
Cathode (negative)
What is the +ve electrode?
Anode (Positive)
Describe what would happen at the -ve electrode in the electrolysis of PbBr₂(l)
Grey/black deposit Pb²⁺ ions attracted Half equation: Pb²⁺ + 2e⁻ -> Pb Gains electrons therefore reduction
Describe what would happen at the +ve electrode in the electrolysis of PbBr₂(l)
Bubbles of red-brown vapour Br⁻ ions attracted half equation: 2Br⁻ -> Br₂ + 2e⁻ Loses electron therefore oxidation
Describe what would happen at the -ve electrode in the electrolysis of NaCl(l)
Grey/black deposit Na⁺ ions attracted half equation: Na⁺ + e⁻ -> Na Gain of electrons therefore reduction
Describe what would happen at the +ve electrode in the electrolysis of NaCl(l)
bubbles of green vapour Cl⁻ ions attracted half equation: 2Cl⁻ -> Cl₂ + 2e⁻ Loses electrons, therefore oxidation
Describe what would happen at the -ve electrode in the electrolysis of Al₂O₃(l)
grey/black deposit Al³⁺ ions attracted half equation: Al³⁺ + 3e⁻ -> Al Gains electrons, therefore reduction