Topic 5 Using Spec Flashcards
What are electrolytes
Ionic compounds that dissolve in water to make a solution that conducts electricity
What happens when ionic compounds are melted or dissolved in water
The ions are free to move around and the liquids will conduct electricity
What are positively charged ions attracted to
Negative electrode ( cathode)
What are negatively charged ions attracted to
Positive electrode (anode)
When do ions attract to the electrode
When a voltage is applied an electrolyte
What happens when an ion touches an electrode
Electrons can be transferred producing elements
What is electrolysis used for
Extracting reactive metals from molten ores
What is the anode usually made of and why
Carbon because it is a good conductor and is cheap
What happens at the cathode
Aluminium is formed
What are disadvantages of electrolysis
Lots of energy needed to produce the electric current
Costs money
Describe copper chloride solution in electrolysis
Applying electricity across copper chloride solution with graphite electrodes produces copper at the cathode and chloride gas at the anode
Describe molten lead bromide in electrolysis
When we use graphite electrodes to apply electricity across molten lead bromide, we form lead (metal) at the cathode and bromine (non-metal) at the anode.
Lead is present if a shiny metal forms around the cathode
Bromine is observed as a brown gas
Describe sodium chloride in electrolysis
Chloride produces hydrogen gas at cathode and chlorine gas at anode
Electrodes are graphite or platinum
Hydrogen can be detected using lit splint and squeaky pop sound
Chlorine gas detected by smell
Describe sodium sulfate in electrolysis
Graphite electrodes
Hydrogen and cathode and oxygen at anode
Hydrogen detected by split and squeaky pop
Oxygen detected by glowing splint
What is produced when halide ions are present at the anode
Respective halogen
What happens if there are no halide ions in the anode
Oxygen forms
What is produced in the cathode when a metal is higher than oxygen in the reactivity series
Hydrogen
What is produced in the cathode when metal is lower than hydrogen in the reactivity series
The metal is produced
In the cathode what half question takes place
Pb2(+) - 2e(-) -> Pb
What half equations takes place at the anode
2Br(-) -> Br2 + 2e(-)
How can you purify copper using copper sulfate in electrolysis
Copper ions will go into the electrolyte solid copper sulfate
The Cu2+ ions will be attracted to the cathode and pure copper will form
What metals are found in the earths crust
Gold and platinum (highly unreactive metals )
What is oxidation
Gain of oxygen and loss of electrons
What is reduction
Loss of oxygen and gain of electrons
What is a displacement reaction
Where a more reactive metal that forms positive ions more easily can remove a less reactive metal from a compound
Describe displacement in terms of oxidation and reduction
More reactive metal loses electrons (oxidation) and the less reactive metal gains electrons (reduction)
What are the 4 stages of life cycle assessment
Collecting the raw materials needed
Making and packaging the product
Product use
Disposal of the product
What are benefits of recycling metals
Less burning of fossil fuels
Less energy used
Conserves finite resources
Fewer waste rock heaps
What does oxidation of metals result In
Corrosion
How can the rusting of iron be prevented
Exclusion of oxygen
Exclusion of water
Sarcrifical protection
What are the three methods to stops metals from corroding
Coatings - apply a coating witch acts like a barrier such as greasing, painting or electroplating
Sarcrifical method - metal that that requires protection will have a more reactive metal attached to it
Galvanising - metal that needs protecting is sprayed With a more reactive metal
Disadvantages of coating
If the coating gets damaged, the metal becomes exposed so corrosion can take place
How can electroplating be used to improve the appearance of a metal
coat a cheaper metal with a more expensive one. This gives the cheaper metal the appearance of the more expensive metal, which could be gold or silver. This gives us the option of buying cheaper jewellery.
How is electroplating used in electrolysis
placing the metal to be electroplated at the negative electrode (cathode) and the coating metal at the positive electrode (anode).
