Electrolysis Flashcards
Explain what is electrolysis
If you pass on electric current through an ionic substance thats molten or in a solution it breaks down into the elements it’s made of this is electrolysis
What does electrolysis require to conduct electricity?
It requires a liquid to conduct electricity called the electrolyte
What do electrolytes contain?
Electrolytes contain free ions . They are usually the molten or dissolved ionic substance
What happens during electrolysis?
Electrons are taken away from ions at the positive electrode and given to other are ions at the negative electrode
What does electrolysis reactions involve?
Oxidation
And
Reduction
What is reduction?
Reduction is the gain of electrons
What is oxidation?
Oxidation is the loss of electrons
What does OIL RIG stand for
Oxidation
Is
Loss
Reduction
Is
Gain
When will a salt conduct electricity?
When it is molten
What does electrolysis mean?
Electrolysis is the splitting up with electricity
When common salt is dissolved in water and electrolysed what three useful products are made?
Hydrogen , chlorine and sodium hydroxide
What is the name of the positive and the negative electrodes?
Positive - anode
Negative - cathode
At which electrode do ions lose electrons through oxidation?
The Anode
At which electrode do ions gain electrons through reduction?
The cathode
What are the two useful products of the electrolysis of sodium chloride solution used in industry?
1) chlorine has many uses such as bleach and plastics
2) sodium hydroxide is a very strong alkali which is used in the chemical industry such as to make soap
How is electrolysis used with aluminium?
Electrolysis is used to remove aluminium from its ore
What is aluminium is ore called?
Bauxite
What is cryolite used to do?
Cryolite is used to lower the temperature (and costs)
What is aluminium and cryolite used to do together and why?
Aluminium oxide is dissolved in molten cryolite because aluminium oxide has a very high melting point of over 2000°C which would be very expensive to melt
Which electrodes are aluminium and oxygen formed at?
Aluminium forms at the negative electrode is an oxygen forms at the positive electrode
What does it mean when oxygen reacts with carbon in the electrode to produce carbon dioxide ?
This means that the positive electrode is gradually getting away and has to be replaced every now and again
What is electroplating?
Electroplating coats one metal onto the surface of another
When electroplating which electrode do you put the metal object you want to plate and the pure metal you want it to be played with
The negative electrode is the metal object you want to plate
The positive electrode is the pure metal you want it to be plated with
How would you electroplate silver onto a Brass cup?
You would make the brass cup of the negative electrode (to attract the positive silver ions). Then you would make a lump of silver the positive electrode. Then you would dip them in a solution of silver ions (e.g silver nitrate)
