Electrolysis Flashcards
What does electrolysis mean?
Ionic compounds that can be broken down using electricity and forming useful elements/compounds
Explain why solid sodium chloride will not conduct electricity like the molten
The ions in solid sodium chloride are not free to move so therefore cannot conduct electricity. But in molten form they are due to being melted to be in liquid form
What is an electrolyte?
Substance that contains free ions, letting it conduct electricity
What does electrolysis need and what are they made from?
Need d.c. and are from graphite or unreactive metals like copper/platinum
What happens during electrolysis?
Cations attracted to cathode where they will gain electrons and so are reduced
Anions are attracted to the anode where they will lose electrons and hence are oxidised
State the two uses of sodium
Street lamps: Yellow light given when electric current passes through sodium vapour in lamp.
Liquid sodium=high ‘heat capacity’ (takes lots of heat energy to raise its temperature). This makes it useful as a coolant in some nuclear power stations
Balance half equations for potassium + chloride. Also state reduction or oxidation
Cathode: K+ (L) + e- —-> K (L) (REDUCTION)
Anode: 2Cl (L) —–> Cl2 (G)+ 2e- (OXIDATION)
What 3 useful industrial products are made by the electrolysis of aqueous sodium chloride?
Hydrogen Chlorine. Sodium hydroxide solution
How is copper purified or refined industrially?
By using electrolysis
Describe how you would purify copper
You put the pure copper at the cathode and the impure at the anode with both in copper sulphate solution. The ions are replaced by copper ions from the impure copper anode. Copper ions move to the copper electrode, gain electrons and are discharged as pure copper
Why do the sludge formed by the impurities below the anode help to reduce the overall cost of purifying copper?
The sludge contains valuable metals like silver, gold, platinum and these can be purified and sold
Hydrogen ions are discharged unless…
Chloride, bromide, or iodide ions are present
Hydrogen ions are discharged unless…
The metal is less reactive than hydrogen
How do you carry out electroplating?
The cathode is where the object to be electroplated is found and the anode is the plating metal. During electroplating, ions from electrolyte (containing ions of the plating metal) move to object and are discharged as metal atoms. They are replaced by ions leaving the anode
