2.5 - Salts And Electrolysis Flashcards
What is the ionic equation for neutralisation?
H + OH -> H2O
What does a pH meter do?
Gives an accurate numerical value for pH
What is concentrated and dilute acids/alkalis?
Concentrated- many particles
Dilute - fewer particles
What is strong and weak acids/alkalis?
Strong - completely ionises
Weak - partially ionises
What does acid + metal produce?
Soluable salt + hydrogen gas
What does acid + base(metal oxide) produce?
Soluable salt + water
What does acid + metal carbonate produce?
Soluable salt + carbon dioxide + water
What does acid + alkali produce?
Soluable salt + water
Name the salts for:
Hydrochloric acid
Sulfuric acid
Nitric acid
Chloride salts
Sulfate salts
Nitrate salts
Why do you need excessive amounts of metals, bases or carbonates?
To make sure all the acid reacts
Excess solid can be removed by filtration
What are ammonium salts used for?
Fertilisers
What does soluable salt + soluable salt produce?
Soluable salt + insoluable salt (precipitate)
Give an example of two soluable salts reaction
Potassium Iodide + Silver Nitrate -> Potassium Nitrate + Silver Iodide (precipitate)
How do you know what the precipitate is in 2 soluable salt reaction?
The least reactive product made
What is electrolysis?
The breaking down of an ionic substance into it’s elements using electricity
What does the substance have to be for electrolysis to work and why?
It has to be dissolved in water or molten. This is because the ions need to be free to move
What does the negatively charged electrode attract?
Positively charged ions (usually metal)
What is the negatively charged electrode called?
Cathode
What does the positively charged electrode attract?
Negatively charged ions
What is the positively charge electrode called?
Anode
What happens at the negative electrode?
Reduction which is the gain of electrons
What happens at the positive electrode?
Oxidation which is the loss of electron(s)
If in a solution what could be produced at the negative electrode?
The positive ion
Metal or Hydrogen
Whichever is the least reactive out of the two
If in a solution what could be produced at the positive electrode?
A halide element (group 7) if not then oxygen
What is produced in the electrolysis of Brine (Sodium Chloride)
Positive electrode: Chlorine
Negative: Hydrogen
Left over: Sodium Hydroxide
How can you test for hydrogen?
Put a lit split into the gas it should make a squeaky pop
How do you test for chlorine?
It bleaches litmus paper
What is chlorine, Hydrogen and sodium hydroxide used in
Chlorine: disinfectant, killing bacteria
Hydrogen: alternative fuel, margarine
Sodium Hydroxide: soap, ceramics, paper, nautralisation
Describe extraction of Aluminium Oxide?
Using electrolysis:
Insoluable so has to be melted
Cryolite added to reduce boiling point from 2700 to 970
This saves energy costs
What is produced at each electrode in the extraction of Aluminium?
Positive: oxygen
Negative: aluminium
If oxygen is produced at the positive electrode in extraction of aluminium oxide what could happen?
As the electrode is made of graphite that is made of carbon
The carbon reacts with the oxygen to produce Carbon dioxide
The electrodes will burn away and have to be replaced
What is electroplating?
Puts a thin coating of metal in an object
To make it more attractive, protect from corrosion or increase hardness
Where is the object placed in electrolysis?
Used as the negative electrode so metal atoms are deposited from the solution on to the object
