Slides in this set
ELECTROLYSIS IS USED TO MAKE
If you pass an electric current through an ionic substance that's molten or in
solution it breaks down into new substances. This is called electrolysis.
It requires a liquid to conduct the electricity, called an electrolyte.
Electrolyte are made by melting or dissolving in ionic compounds.
In either cases it's the free ions which conduct the electricity.
For the circuit to be complete, there's got to be a flow of electrons. Electrons
are taken away from ions at the positive electrode (Anode) and given to other
ions at a negative electrode (cathode).
As ions gain or lose electrons they become atoms or molecules.…read more
ELECTROLYTES ARE LIQUIDS
THAT CONDUCT ELECTRICITY
When you place a conductivity probe in an electrolyte, current flows through
the circuit- so you can measure it's conductivity.
When you place a conductivity probe in a non-electrolyte, no current flows,
so you'll get a reading of zero conductivity.
Another way of determining whether a substance is an electrolyte or not is to
set up an electrolytic cell.
If the substance will undergo electrolysis then it is an electrolyte.…read more
IN MOLTEN IONIC
COMPOUNDS THERE'S ONLY
ONE SOURCE OF IONS
Molten ionic compounds can be electrolysed because the ions can move
They are usually broken up into their elements.
A good example of this is the electrolysis of molten lead bromide (PbBr2)
-ve ions are called
+ve ions are called ANIONS, because
CATIONS, because They're attracted
They're attracted To the +ve Anode
To the ve cathode…read more
ELECTROLYSIS OF AQUEOUS
In aqueous solutions, as well as the ions from the ionic compound, there will
be hydrogen ions (H+) and Hydroxide ions (OH-) from the water.
At the cathode, if H+ ions are present, hydrogen gas will be produced if the
metal ions are more reactive than the H+ ions. If the metal ions are less
reactive than the H+ ions a solid layer of pure metal will be produced instead.
At the Anode, if OH- and halide ions (Cl-,Br-,I-) are present, molecules of
chlorine bromine or iodine will be formed. If no halide ions are present, then
oxygen will be formed.
EXAMPLE 1- SULFURIC ACID
A solution of sulphuric acid contains three different
Hydrogen ions (from the water or sulphuric acid)
accept electrons. So at the cathode, hydrogen gas is produced.
2H+ + 2e- H2
Hydroxide ions lose electrons more easily than
Sulfate ions. So at the Anode Oxygen and water are produced.
4OH- O2 + 2H2O + 4e-…read more