Electrolysis Flashcards
What is electrolysis?
the decomposition of a substance that is molten or in solution by passing an electric current through it
What is an electric current?
flow of electrons (or ions)
What is an electrolyte?
a substance that undergoes electrolysis
What is an electrode?
a substance that can pass electricity into and out of the electrolyte
What is an electrode made out of?
inert material so that it does not take part in the reaction
What is an anode?
positive electrode
What happens to the electrons at the anode?
they are taken away from the ions at the anode
What is a cathode?
negative electrode
What happens to the electrons at the cathode?
electrons from the anode are given to the ions at the cathode
What must an electrolyte contain?
ions to allow current to flow in the circuit
How are electrolytes made?
melting compounds
dissolving ionic compounds
How to test for an electrolyte
- use a conductivity probe - if it gives a reading of zero then it is a non-electrolyte
- set up an electrolytic cell - if it undergoes electrolysis then it is an electrolyte
In molten compounds, what is formed at the anode?
non-metals
In molten compounds, what is formed at the cathode?
metals
How many ions are there in an aqueous solution?
4 ions
- 2 from salt
- 2 from water
What happens at the anode in sodium chloride solution?
- chlorine and hydroxide ions are attracted to anode
there are more chlorine ions so they are discharged
(hydroxide ions make the solution around the cathode alkaline so forms sodium hydroxide)
What happens at the cathode in sodium chloride solution?
- sodium and hydrogen ions are attracted to anode
- hydrogen ions discharge and combine to form hydrogen
What happens at the anode in copper sulfate solution?
hydroxide ions are discharged
