Questions and Answers
Which compound is used as the electrolyte in the electrolysis of water?
What is produced at the anode during the electrolysis of water?
What occurs to the mass of the anode during the electrolysis of CuSO4 solution?
In the dissociation of water, which ions are produced?
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What type of reaction occurs at the cathode during the electrolysis of CuSO4 solution?
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Which statement is true regarding the conductivity of electrolyte solutions?
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In an electrochemical cell, what energy conversion takes place?
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What occurs at the cathode during an electrochemical reaction?
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During the process of electrolysis, what happens to the electrical energy?
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Which statement correctly describes the behavior of ions in solution?
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What is the role of cryolite in the extraction of aluminium?
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Which reaction represents the process occurring at the anode during aluminium extraction?
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What is the product formed at the cathode during copper plating?
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At what temperature is the extraction of aluminium primarily conducted?
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Which equation represents the dissociation of nickel sulfate in nickel plating?
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Which of the following represents the dissociation of cryolite during the extraction process?
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In gold plating, what is the effect of electrons at the cathode?
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What is produced at the cathode during the extraction of aluminium?
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Which of the following is the correct reaction occurring at the anode during nickel plating?
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Which electrolyte is used for gold plating?
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What is the composition of the electrolyte used in the electrorefining of copper?
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In the electrorefining process, which of the following reactions occurs at the cathode?
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What is the primary purpose of using a lead lined voltameter in the electrorefining of copper?
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What is the percentage of purity of blister copper before the electrorefining process?
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Which component serves as the anode in the electrorefining of copper?
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Study Notes
Electricity & Chemical Reactions
- Conductivity in dilute electrolyte solutions is higher than in concentrated solutions.
- Electrolytes dissociate into cations and anions when molten or in aqueous solution.
- The total charge of ions remains constant throughout the process.
- In metals, electricity is conducted by electrons; in electrolytes, it is conducted by ions.
- Electrochemical cells convert chemical energy into electrical energy.
- Water possesses a high dielectric constant, affecting its electrical properties.
- During electrolysis, electrical energy is converted into chemical energy.
- Reduction happens at the cathode, while oxidation occurs at the anode.
Electrolysis of Water
- An electrolyte for water electrolysis can be water mixed with 2% H2SO4.
- Hoffman's Voltameter is the apparatus used for the electrolytic cell.
- Electrodes used are platinum for both cathode and anode.
- The dissociation of water: H2O(l) → H+(aq) + OH-(aq) and H2SO4(l) → 2H+(aq) + SO42-(aq).
- Cathode reaction involves reduction: 4H+(aq) + 4e- → 2H2(g).
- Anode reaction involves oxidation: 4OH-(aq) - 4e- → 2H2O(l) + O2(g).
Electrolysis of CuSO4 Solution
- CuSO4 dissociates in solution: CuSO4(aq) → Cu2+(aq) + SO42-(aq).
- Cathode reaction produces solid copper: Cu2+(aq) + 2e- → Cu(s).
- Anode reaction involves oxidation of solid copper: Cu(s) → Cu2+(aq) + 2e-.
- The mass of the anode decreases during the process.
Applications of Electrolysis
-
Copper Plating:
- CuSO4 dissociates: CuSO4(aq) → Cu2+(aq) + SO42-(aq).
- At the cathode: Cu2+(aq) + 2e- → Cu(s).
- At the anode: Cu(s) → Cu2+(aq) + 2e-.
-
Nickel Plating:
- NiSO4 dissociates: NiSO4(aq) → Ni2+(aq) + SO42-(aq).
- At the cathode: Ni2+(aq) + 2e- → Ni(s).
- At the anode: Ni(s) → Ni2+(aq) + 2e-.
-
Gold Plating:
- Uses K[Au(CN)2] as the electrolyte.
- Cathode reaction: Au+ + e- → Au.
- Anode reaction: Au → Au+ + e-.
-
Silver Plating:
- Utilizes K[Ag(CN)2] as the electrolyte.
- Cathode reaction: Ag+ + e- → Ag.
- Anode reaction: Ag → Ag+ + e-.
Extraction of Aluminium
- Production involves alumina (Al2O3) at 20% and cryolite (AlF3, 3 NaF) at 60%.
- Requires heating to 900°C.
- Electrodes used: graphite for anode and collection of Al at the cathode.
- Key dissociation reactions:
- AlF3, 3 NaF → AlF3 + 3NAF 3 NaF
- AlF3(l) → Al3+(l) + 3F−(l)
- Al2O3(l) → 2Al3+(l) + 3O2−(l).
- Cathode reaction produces aluminum: Al3+ + 3e- → Al.
- Anode reaction generates oxygen: 3O2− - 6e- → 3O, which can form O2.
Electrorefining of Copper
- Blister copper, impure (97-98% Cu), undergoes electrolysis to refine to 99-99.99% purity.
- Electrolyte used is a mixture of 15% CuSO4 and 5-10% H2SO4.
- The cathode consists of a pure copper plate, while the anode is an impure copper block.
- The lead-lined voltameter is the apparatus used.
- Reactions occurring during electrorefining:
- CuSO4(aq) dissociates to Cu2+(aq) + SO42−(aq).
- At the cathode: Cu2+(aq) + 2e- → Cu.
- At the anode: Cu(s) - 2e- → Cu2+(aq).
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Description
This quiz explores the fundamental principles of electricity related to chemical reactions. It covers topics such as conductivity in electrolytes, ionization processes, and the conversion of chemical energy to electrical energy. Test your knowledge on how ions and electrons contribute to electrical conductivity in different states.
