Electrolytic Processes Flashcards
State the meaning of the term ‘electrolyte’.
An electrolyte is a substance that conducts electricity when it is molten or dissolved in water, breaking down into ions that enable electrolysis.
Outline what happens during electrolysis.
In electrolysis, an electric current passes through an electrolyte, causing ions to move to the electrodes. At the electrodes, ions gain or lose electrons, resulting in the formation of elements or compounds.
Explain the movement of the ions during electrolysis.
Positive ions (cations) move toward the cathode (negative electrode) where they gain electrons, while negative ions (anions) move toward the anode (positive electrode) where they lose electrons.
Write half equations for the reactions at the electrodes.
For example, in the electrolysis of copper(II) chloride:
At the cathode:
Cu^2+ + 2e^−→Cu
At the anode:
2Cl^− → Cl2 + 2e^−
Explain the meaning of oxidation and reduction in terms of the movement of electrons.
Oxidation is the loss of electrons, while reduction is the gain of electrons.
State the electrodes at which oxidation and reduction occur.
Oxidation occurs at the anode (positive electrode), and reduction occurs at the cathode (negative electrode).
Recall the products formed from the electrolysis of a variety of common compounds and solutions (e.g., copper chloride solution, sodium chloride solution, etc.).
Copper chloride solution: Copper (cathode) and chlorine gas (anode)
Sodium chloride solution: Hydrogen gas (cathode) and chlorine gas (anode); sodium hydroxide forms in the solution.
Acidified water: Hydrogen gas (cathode) and oxygen gas (anode).
Molten lead bromide: Lead (cathode) and bromine gas (anode).
Explain the formation of the products in the electrolysis of common compounds.
Each compound dissociates into ions that move to respective electrodes; for example, in sodium chloride solution, H^+ ions are reduced to form H2 at the cathode, and
Cl^− ions are oxidized to form
Cl2 gas at the anode.
Predict the products formed from the electrolysis of a molten, binary, ionic compound.
The products are the element of the metal cation at the cathode and the non-metal anion at the anode, e.g., molten lead bromide produces lead at the cathode and bromine gas at the anode.
Explain how electrolysis of copper sulphate solution using copper electrodes can purify copper.
The impure copper anode dissolves into the solution, depositing pure copper on the cathode, while impurities form sludge at the bottom.
