Salts and electrolysis Flashcards
When acids are added to water, what do they produce?
Hydrogen.
What are bases?
Substances that will neutralise acids and produce salts.
What is an aqueous solution?
The mixture made by adding a soluble substance to water.
Alkalis dissolve in water to produce what?
Hydroxide ions.
Some salts can be made by the reaction of a metal with an acid. This produces what?
Hydrogen gas.
Salts can be crystallised by doing what?
Evaporating off water.
How can insoluble salts be made?
Reacting two solutions to produce a precipitate.
What is precipitation and why is it important?
An insoluble solid formed by a reaction taking place in a solution and it is important in removing some metal ions from industrial waste water.
What does electrolysis do?
Splits up a substance using electricity.
How can ionic compounds be electrolysed?
When they are in molten or in solution because their ions are free to move to their electrodes.
What does inert mean?
Unreactive
Negative ions lose electrons and are oxidised at the positive electrode. What happens at the positive side?
Gain electrons and so they are reduced at the negative side.
What gas is produced when aqueous solutions are electrolysed? (Positive side)
Oxygen gas unless it contains halide ions.
What gas is produced when aqueous solutions are electrolysed? (Negative side)
Hydrogen unless the solution contains ions of a metal that is less reactive than hydrogen.
Why is aluminium oxide mixed with molten cryolite?
To lower its melting point.
