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Questions and Answers
What happens to the mass of the anode during the electrolysis of copper(II) sulfate?
What happens to the mass of the anode during the electrolysis of copper(II) sulfate?
The concentration of Cu2+ ions in the solution changes during the electrolysis process.
The concentration of Cu2+ ions in the solution changes during the electrolysis process.
False
What is the product formed at the cathode during the electrolysis of concentrated copper(II) sulfate solution?
What is the product formed at the cathode during the electrolysis of concentrated copper(II) sulfate solution?
Copper
What gas is produced at the anode when electrolysis occurs with dilute barium chloride solution?
What gas is produced at the anode when electrolysis occurs with dilute barium chloride solution?
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During the electrolysis of dilute sodium chloride, the product at the anode is __________.
During the electrolysis of dilute sodium chloride, the product at the anode is __________.
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In electrolysis, if a metal is above hydrogen in the reactivity series, hydrogen will be produced at the cathode.
In electrolysis, if a metal is above hydrogen in the reactivity series, hydrogen will be produced at the cathode.
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Match the aqueous solutions with their respective products at the anode:
Match the aqueous solutions with their respective products at the anode:
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What is the role of the cathode in electrolysis?
What is the role of the cathode in electrolysis?
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If the metal is below hydrogen in the reactivity series, the ______ metal ions are discharged.
If the metal is below hydrogen in the reactivity series, the ______ metal ions are discharged.
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Match the following ions with their sources in aqueous copper sulfate:
Match the following ions with their sources in aqueous copper sulfate:
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What product is formed at the cathode during the electrolysis of copper(II)sulfate?
What product is formed at the cathode during the electrolysis of copper(II)sulfate?
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During electrolysis, OH– ions are discharged at the cathode.
During electrolysis, OH– ions are discharged at the cathode.
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The half equation for the reaction at the cathode is _____ + 2e– → Cu.
The half equation for the reaction at the cathode is _____ + 2e– → Cu.
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Match the following reactions with their corresponding electrode:
Match the following reactions with their corresponding electrode:
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Which ion is attracted to the anode?
Which ion is attracted to the anode?
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Cations are negatively charged ions attracted to the anode.
Cations are negatively charged ions attracted to the anode.
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What mnemonic can be used to remember the charge of electrodes during electrolysis?
What mnemonic can be used to remember the charge of electrodes during electrolysis?
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During electrolysis, positive ions move towards the ______.
During electrolysis, positive ions move towards the ______.
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Match the following terms with their corresponding descriptions:
Match the following terms with their corresponding descriptions:
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What forms at the cathode during the electrolysis of metals?
What forms at the cathode during the electrolysis of metals?
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Electrolysis requires a supply of electrons at the anode.
Electrolysis requires a supply of electrons at the anode.
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What are the charge carriers in the external circuit during electrolysis?
What are the charge carriers in the external circuit during electrolysis?
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What is the primary function of an electrolyte in electrolysis?
What is the primary function of an electrolyte in electrolysis?
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Covalent compounds can conduct electricity and undergo electrolysis.
Covalent compounds can conduct electricity and undergo electrolysis.
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What happens to ionic compounds when an electric current is passed through them while in the molten state?
What happens to ionic compounds when an electric current is passed through them while in the molten state?
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The positive electrode in an electrolysis cell is called the ______.
The positive electrode in an electrolysis cell is called the ______.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What does oxidation involve?
What does oxidation involve?
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Reduction occurs at the anode.
Reduction occurs at the anode.
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What happens to negatively charged ions at the anode?
What happens to negatively charged ions at the anode?
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In an ionic half-equation, reduction shows the gain of ______.
In an ionic half-equation, reduction shows the gain of ______.
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Match the following types of ions with their respective behavior during electrolysis:
Match the following types of ions with their respective behavior during electrolysis:
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Which ionic half-equation represents the reduction of copper ions?
Which ionic half-equation represents the reduction of copper ions?
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Ionic half-equations must show both oxidation and reduction in a single equation.
Ionic half-equations must show both oxidation and reduction in a single equation.
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What does a charge of '+2' on an ion indicate regarding the number of electrons gained upon reduction?
What does a charge of '+2' on an ion indicate regarding the number of electrons gained upon reduction?
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Study Notes
Electrolysis Principles
- Electrolysis is the process of decomposing a compound using an electric current
- Molten ionic compounds and aqueous solutions of ionic compounds can be electrolysed
- Covalent compounds cannot be electrolysed as they do not conduct electricity in the solid or liquid state
- Ions in ionic compounds can move and carry charge when molten or dissolved in solution, allowing them to conduct electricity
Electrical Conductivity of Ionic Compounds
- Solid ionic compounds do not conduct electricity because the ions are fixed in place.
- Molten or dissolved ionic compounds conduct electricity because the ions are free to move.
Key Terms in Electrolysis
- Electrode: A rod of metal or graphite conducting an electrical current into or out of an electrolyte.
- Electrolyte: A molten or dissolved ionic compound that conducts electricity.
- Anode: The positive electrode in an electrolysis cell
- Cathode: The negative electrode in an electrolysis cell
- Anion: A negatively charged ion, attracted to the anode.
- Cation: A positively charged ion, attracted to the cathode
Electrolysis Principles - Extended Tier
- During electrolysis, a current flows around a circuit requiring charge to be carried
- Power supply provides electrons to the cathode, making it negatively charged
- Positive ions (cations) in the electrolyte move towards the cathode, where they gain electrons
- Negative ions (anions) in the electrolyte move towards the anode, where they lose electrons
- Electrons move from the anode back to the power supply, completing the circuit
- Electrons are charge carriers in the external circuit, while ions are charge carriers within the electrolyte.
Electrolysis of Molten Compounds (e.g., Lead(II) Bromide)
- A binary ionic compound is made of two elements joined by ionic bonds
- Electrolysis of molten lead (II) bromide produces lead metal at the cathode and bromine gas at the anode
- To heat up the substance and allow the ions to move and conduct electricity
- Adding lead(II) bromide into a beaker, and heating up until molten
- Placing two graphite rods as electrodes and connecting them to a power pack or battery
- Turning on the power pack to allow electrolysis
Electrolysis of Aqueous Solutions (e.g., Sodium Chloride)
- Brine is a concentrated solution of sodium chloride
- Electrolysis using inert electrodes (e.g., platinum or graphite) as they do not participate in the reaction
- Ions present in brine are Na+, Cl-, H+, and OH-
- Electrolysis produces hydrogen gas at the cathode and chlorine gas at the anode.
- Sodium hydroxide remains in the solution.
Electrolysis of Dilute Sulfuric Acid
- Electrolysis of dilute sulfuric acid uses inert electrodes to create hydrogen gas at the cathode and oxygen gas at the anode.
- The ions present are H+, SO4-2, and H2O, which dissociates to H+ and OH-
Electrolysis of Aqueous Copper Sulfate
- Electrolysis of aqueous copper sulfate uses inert electrodes.
- Copper is produced at the cathode and oxygen gas is produced at the anode
- The cathode increases in mass as copper atoms are deposited onto it
- The anode decreases in mass.
Ionic Half-Equations (Extended Tier Only)
- Oxidation is the loss of electrons, reduction is the gain of electrons
- Ions in electrolysis will gain or lose electrons at electrodes
- Half-equations show the exact electron gain or loss during a redox reaction at an electrode.
- Ions are reduced at the cathode and oxidised at the anode; this produces new neutral atoms in the products.
Writing Ionic Half-Equations
- Metals are positive ions (e.g., Li+, Cu2+, Al3+)
- For non-metals (e.g., Cl-, Br-, OH-)
- Important in electrochemistry
- Hydrogen ions/hydrogen half-equation
- Halide ions/halogen half equation
- Hydroxide ion/oxygen half-equation
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Description
Explore the essential concepts of electrolysis and electrical conductivity of ionic compounds. This quiz covers key terms, the role of electrodes, and the reasons why solid and molten ionic compounds behave differently in terms of conducting electricity. Test your knowledge on the fascinating world of electrochemistry!
