Electrolysis Flashcards
What does an electrolytic cell consist of
- Battery
- Electrodes
- Electrolyte
Which is the positive electrode
Anode
What are some weak electrolytes
- Weak acids and alkalis
Which is the negative electrode
Cathode
Define electrolysis
Electrolysis is the chemical decomposition of a compound by passing electricity through the compound when molten or aqueous
Define an electrolyte
An electrolyte is a compound which when molten or aqueous, conducts electricity with its decomposition at the electrodes
What reaction takes place at the cathode
Reduction
What are some strong electrolytes
- Strong acids and alkalis
- Salt solutions
What reaction takes place at the anode
Oxidation
Define a binary compound
A binary compound is a compound containing only 2 elements
Why are there OH- and H+ ions in aqueous solutions
Water undergoes reversible self-ionisation to produce a small concentration of OH- and H+ ions
What are the factors affecting the discharge of ions during electrolysis
- Relative position of ions in electrochemical series
- Relative concentration of ions
- Nature of electrode
Why will the ion that is lower in the electrochemical series be preferentially discharged
- Ion is less stable
- Ion gains electrons more easily to be discharged as a metal
Which anions are usually not discharged
- F-
- SO42-
- NO3-
Define electroplating
Electroplating is the coating of the surface of an object with a thin layer of a metal by electrolysis
What is the equation for discharge of hydroxide ions
4OH-
–> 2H2O + O2 + 4e-
In electrolysis, where is the object to be coated placed
Cathode
What impurities are found in impure copper
Silver and gold
How can the thickness of electroplating be adjusted
Adjusting:
- Magnitude of current
- Time duration of process
What is a simple cell
A simple cell is a device that converts chemical energy to electrical energy
Which is the negative electrode in a simple cell
More reactive metal
How do electrons flow in a simple cell
From more reactive metal to less reactive metal
Which is the positive electrode in a simple cell
Less reactive metal
Where does reduction occur in a simple cell
Positive electrode
How to increase voltage produced in a simple cell
Use metals for the electrodes that are far apart in the reactivity series
When will the voltmeter read 0V in a simple cell
When electrodes are made of the same metal
Define a fuel cell
A fuel cell is a chemical cell in which reactants are continuously supplied to produce electricity directly
Where is the negative electrode in a fuel cell
Side where fuel enters
Where is positive electrode in fuel cell
Side where oxygen enters
How do electrons flow in a fuel cell
From negative to positive electrode
