C2.5 Salts and Electrolysis Flashcards
Acids ionise in water to produce….
hydrogen ions H+
Alkalis ionise in water to produce….
Hydroxide ions, OH-
What is a base?
A substance that neutralises an acid
Suggest the pH of hydrochloric acid
1-4
Suggest the pH of sodium hydroxide
10-14
Acid + Metal =
Salt + Hydrogen
MASH
Acid + Metal Oxide =
Salt + Water
Acid + Alkali =
Salt + Water
Acid + Metal Carbonate =
Salt + carbon dioxide + water
Magnesium + Hydrochloric acid =
Magnesium Chloride + Hydrogen
Sodium Hydroxide + Nitric acid =
Sodium nitrate + water
Copper Oxide + sulphuric acid =
Copper sulphate + water
Calcium Carbonate + Hydrochloric acid =
Calcium chloride + Carbon Dioxide + water
List the steps to make copper sulphate crystals
Warm sulphuric acid
Add copper oxide until it is in excess
Filter the excess copper oxide
Evaporate the water
Lead nitrate + Potassium Iodide =
Lead iodide + Potassium nitrate
How can a precipitate, such as lead iodide, be removed from a solution?
Filter it
What is the positive electrode in electrolysis called?
Anode
PANic
What is the negative electrode in electrolysis called?
Cathode
PANiC
In the electrolysis of lead iodide, why does the lead iodide have to be melted?
so the ions can move
and carry the charge
In the electrolysis of lead iodide, which electrode do the lead ions go to?
Cathode
Explain why copper ions go to the cathode
The cathode is negative
Copper ions are positive
Opposite charges attract
Explain why chloride ions go to the anode
The anode is positive
Chloride ions are negative
Opposite charges attract
Finish the following equation
Pb2+ + __ e- –> Pb
Pb2+ + 2e- –> Pb
Finish the following equation
_Cl- —> Cl2 + __e-
2Cl- —> Cl2 + 2e-
How does a copper ion, Cu2+, become a copper ion?
By gaining two electrons
What is the aluminium ore called?
Bauxite
Why is molten cryolite added to the bauxite?
To reduce the melting point
so less energy is required
Name the three products of the electrolysis of brine
Sodium hydroxide
Hydrogen
Chlorine
(CatHy’s AnCls)
The loss of electrons is called
Oxidation
OILRIG
The gain of electrons is called
Reduction
OILRIG
Why is hydrogen produced instead of sodium in the electrolysis of brine?
Sodium is more reactive than hydrogen
Why is electroplating used?
To make objects look better
To protect the metal from corroding
It’s cheaper than using the pure metal