C6 Flashcards
What is an electrolyte?
An electrolyte is just a liquid or solution that can conduct electricity.
What is an electrode?
An electrode is a solid that conducts electricity and is submerged in the electrolyte
During electrolysis, where does an electric current pass through
An electrolyte. The ions move towards the electrodes, where they react, and the compound decomposes
The positive ions in the electrolytewill move towards the _______ (-ve electrode) and gain electrons (they are __________). The megative ions in the electrolyte more towards the ______ (ve+ electrode) and lose electrons (they are __________)
Cathode, reduced
Anode, oxidised
As ions gain or lose electrons, they form the _____________ _____________ and are _______ from the electrolyte
Uncharged element, discharged
The ionic compound that is broken down by an electric current in electrolysis is called the
Electrolyte
In electrolysis, why do positively charged ions move to the negstive electrode and the negative ions move towards the positive electrode
As opposite charges attract
Can ionic compounds be electrolysed? If not why
Because ions are in fixed positions and can’t move
Molten ionic compounds can or cannot be electrolysed
They can as the ions can move freely and conduct electricity
Molten ionic liquids (lead bromide, are always broken up into their elements. Positive metal ions are reduced to the element at the csthode:
Negative non-metal ions are oxidised to the element at the anode:
Pb2+ + 2e- ~ Pb
2Br- ~ Br2 + 2e-
Extracting metals using electrolysis is:
Very expensive aslots of energy is required to melt the ore and produce the reauired current.
The extraction of aluminium from its ore by using electrolysis
-It is extracted from the ore Baixite by electrolysis. Contains aluminium oxide.
- aluminium oxide has very high melting temperature so it’s mixed with cryolite to lower the melting point
- the molten mixture contains free ions - so it’ll conduct electricity.
-the positive Al3+ ions are attracted to the negstive electrode where they each pick up three electrons and turn into nuetral aluminium atoms. These then sink to the bottom of the electrolysis tank
- the negative O2- ions are attracted to the positive electrode where they each lose two electrons, the nuetral oxygen atoms will then combine to form o2 molecules
EXTRACTION OF ALUMINIUM FROM BAUXITE BY ELECTROLYSIS
INSERT PIC from pahe 58 cgp
In aqueous solutions, as well as the ions from the ionic compound, there will be
Hydrogen ions and hydroxide ions from the water
At the cathode, if H+ ions and metal ions are present, ________ ____ will be produced if the metal ions form an elementsl metal that is _____ reactive than hydrogen. If the metal ions form an elemental metal that is _____ reactive than hydrogen, a solid layer of the _____ ______ will be produced
Hydrogen gas, more, less, pure metal
At the ______, if OH- and halide ions are present, molecules of chlorine, bromine or iodine will be formed. If no ______ _____ are present, then the OH- ions are discharged and ______ will be formed
Anode, halide ions, oxygen
What do half equations show?
They show the reactions at the electrodes.
One thing you must remember when combining half equations is?
The number of electrons needs to be the same for each half equation. Insert example from page 59 bottom of page
What happens to chlorine, hydrogen and oxygen in experiments?
Chlorine bleaches damp litmus paper, turning it white, hydrogen makes a squeaky pop with a lighted splint, oxygen will relight a glowing splint
A solution of copper (II) sulfate contains four different ions:
Cu2+, SO4 2-, H+ and OH-
Copper metal is _____ reactive than hydrogen so
Less
At the cathode, copper metal is produced and coats the electrode
INSERT PIC OF CUSO4 SOLUTION IN ELECTROLYSIS PAGE 59
(Copper sulfste solution is electrolysis)
There aren’t any halide ions present. So at the anode oxygen and water are
Produced. The oxygen can be seen as bubbles.
A solution of sodium chloride (NaCl) contains four different ions:
Na+, Cl-, OH-, H+
Insert pic of NaCl solution in page 59 electrolysis
Copper metal is ____ reactive than hydrogen. So at the cathode, _________ ____ is produced.
More, hydrogen gas.
Electrolysis of aqueous solution sodium chloride
Chloride ions are present in the solution. So at the ______ chlorine gas is produced
Anode
