Eletrolysis Flashcards
What is electrolysis?
The decomposition of a compound using electricity.
What is the electrolyte in electrolysis?
The compound (molten or aqueous) that is being decomposed by the electricity.
What is the positive electrode called in electrolysis?
Anode.
What type of ions are attracted to the anode?
Anions / negative ions.
What occurs at the positive electrode during electrolysis?
Negatively charged ions lose electrons - oxidation.
What is the negative electrode called in electrolysis?
Cathode.
What type of ions are attracted to the cathode?
Cations / positive ions.
What occurs at the negative electrode during electrolysis?
Positively charged ions gain electrons - reduction.
What happens to solid ionic compounds during electrolysis?
The ions are in a fixed lattice and are not free to move.
What is the state of ionic compounds that allows them to conduct electricity?
Molten or aqueous.
What do molten ionic liquids split into during electrolysis?
Their elements.
What is produced at the cathode during electrolysis?
Metals.
What is produced at the anode during electrolysis?
Non-metals.
What makes the electrolysis of aqueous ionic compounds more complicated?
The presence of more ions, including H+ and OH- ions.
At the cathode, what determines whether a metal ion or hydrogen forms?
The reactivity of the metal compared to hydrogen.
If the metal is less reactive than hydrogen, what will form at the cathode?
The metal.
At the anode, what competes for discharge against non-metals?
OH- ions.
If the non-metal is a halide (F, Cl, Br, I), what will always be discharged at the anode?
The halogen.
What is an example of a halogen forming during electrolysis?
Chloride becoming chlorine (Cl2).
What occurs if the non-metal is not a halide during electrolysis?
OH- will discharge into O2 + H2O.
What is one way to set up an electrolysis experiment to obtain gas?
Using inverted test tubes or a gas syringe.
What is the test for chlorine gas?
It bleaches damp litmus paper, turning it white.
What sound does hydrogen make when burned with a lighted splint?
A squeaky pop.
What happens to a glowing splint in the presence of oxygen?
It relights.
What is the primary ore of aluminium?
Bauxite (Al2O3).
How are metals extracted from their ores using electrolysis?
By melting the ore and producing the required current.
Why is electrolysis used for extracting certain metals?
When the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.
What is the role of cryolite in the extraction of aluminium?
It lowers the operating temperature by allowing the mixture to move freely at a lower temperature.
What do the positive Al³⁺ ions do during electrolysis?
They are attracted to the negative electrode, pick up three electrons each, and turn into neutral aluminium.
What do the negative O²⁻ ions do during electrolysis?
They are attracted to the positive electrode, lose two electrons, and form neutral oxygen atoms.
What is a consequence of using carbon electrodes in electrolysis?
The anodes need to be replaced often as they react with oxygen to form carbon dioxide.
What do half equations show?
The reactions that happen at the electrodes.
Fill in the blank: For the electrolysis of aqueous sodium chloride, the half equation for hydrogen is _______.
2H⁺ + 2e⁻ → H₂
What is the ionic equation for the electrolysis of aqueous sodium chloride?
2H⁺ + 2Cl⁻ → H₂ + Cl₂
What is a method to obtain copper from copper sulfate?
By displacement with scrap iron or by electrolysis.
What are the two processes mentioned for obtaining copper from ores?
- Bioleaching
- Phytomining
