Electrolysis Flashcards
What is a redox reaction?
It is a reaction in which one substance is being oxidized and the other substance is being reduced.
What is electrolysis? And what is electrolyte?
Breakdown of ionic substances by using electricity/ an electric current
Electrolyte is a substance that is able to conduct electricity. It is the solution in the beaker.
What are the charges for cathodes, anodes, cations, anions?
Cathodes are negative
Anodes are positive
Cations are negative
Anions are positive
Why do metals move to the cathodes electrode?
Because metals such as copper, zinc, etc are positively charged which means that they are attracted to the oppositely charged ions which are negative ions and so they will be attracted to the cathodes.
Why do non-metals move to the anodes electrode?
Because non metals are negative and so they will be attracted to the oppositely charged ions which is why they move to the anode electrode because anodes are positive.
What compounds are used for electrolysis?
Ionic compounds
What are the requirements for electrolytes?
It should be molten or dissolved so that the ions can move around freely to carry the current
It should be an ionic compound
What happens after the ions move to the electrodes? Explain what would happen to metals and non metals
Ions start gaining or losing electrons depending on their charge, they’ll be able to change into their compound form.
Metals will be reduced into element form.
Non metals will be oxidized into diatomic form.
What are halides and what are the most common halides?
Halides are atoms with a negative charge.
Fluoride, iodide, chloride, bromide
Why are some metals extracted by using electrolysis?
Some metals are more reactive THAN CARBON. So they cannot be extracted by reduction with carbon,so they’re extracted by electrolysis.
Why is aluminum mixed with cryolite?
Because Al has a very high melting point which means it will be very expensive to melt it, and so it mixed with cryolite
Explain the difference in the processes in electrolysis and in a chemical cell-
electrolysis uses electricity to produce a chemical reaction whilst chemical cell uses the chemical reaction to produce electricity.
Do the positive ions need to lose or gain electrons to form an atom?
They need to gain electrons
Do the negative ions need to lose or gain electrons to form an atom
They need to lose electrons to form an atom
Why do water molecules ionise?
To form H+ and OH- ions (hydrogen and hydroxide)
What does aqueous mean? And how do the ions that will be produced in the electrodes relate to the reactivity series?
Aqueous means dissolved in water.
At the electrodes, if the ions are higher in reactivity than H+ ions, then H2 ions will be formed. (For example- if sodium was present, then H+ will be formed)
If the ions present are lower in reactivity than H+ ions, then the metal present will be formed. (For example- if copper was present then it will be produced)
State the reactivity series-
Potassium
Sodium
Calcium
Magnesium
Aluminum
Carbon
Zinc
Iron
Tin
Leads
Hydrogen
Copper
Sliver
Gold
Why do ionic compounds that are in solid states do not conduct electricity?
Because they’re bonded together and are fixed in place so the ions are not capable of moving freely to carry the current
Why do the electrodes need to be un reactive? And what could be used as the electrode?
Electrodes need to be inert (un reactive) to avoid any chemical reactions (platinum) can be used as an electrode
Why will oxygen gas be produced at the anode if a halide is not present? Write the equation for the reaction of hydroxide-
Because 4 hydroxide ions react to form oxygen gas, water and the ions lose 4 electrons in the process since they moved to the anode to lose electrons to form atoms.
4 OH- —> O2 + 2H2O + 4e-
What happens to the hydroxide ions at the positive electrode?
They lose electrons, to form oxygen gas and water
