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Questions and Answers
Which of these factors is NOT a key factor influencing corrosion?
Which of these factors is NOT a key factor influencing corrosion?
What is the purpose of the electrolyte in a fuel cell?
What is the purpose of the electrolyte in a fuel cell?
What is the primary advantage of using a fuel cell over a lead storage battery?
What is the primary advantage of using a fuel cell over a lead storage battery?
During the operation of a lead storage battery, what happens to the concentration of sulfuric acid?
During the operation of a lead storage battery, what happens to the concentration of sulfuric acid?
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What is the chemical reaction occurring at the cathode of a fuel cell?
What is the chemical reaction occurring at the cathode of a fuel cell?
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What is the main advantage of using a sacrificial protection method to prevent corrosion?
What is the main advantage of using a sacrificial protection method to prevent corrosion?
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How can the molar conductivity of a strong electrolyte at infinite dilution be obtained?
How can the molar conductivity of a strong electrolyte at infinite dilution be obtained?
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What is the main function of the porous carbon electrodes in a fuel cell?
What is the main function of the porous carbon electrodes in a fuel cell?
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What is the relationship between molar conductivity (Λm) and concentration (c) for a weak electrolyte?
What is the relationship between molar conductivity (Λm) and concentration (c) for a weak electrolyte?
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What is the significance of the Debye-Hückel-Onsager equation?
What is the significance of the Debye-Hückel-Onsager equation?
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Why is the hydroxide concentration higher near the cathode than the anode in a fuel cell?
Why is the hydroxide concentration higher near the cathode than the anode in a fuel cell?
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According to Kohlrausch's law, what is the contribution of an ion to the molar conductivity of an electrolyte at infinite dilution?
According to Kohlrausch's law, what is the contribution of an ion to the molar conductivity of an electrolyte at infinite dilution?
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What is the principle behind the construction of a battery?
What is the principle behind the construction of a battery?
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Which of the following is NOT a requirement for a good battery?
Which of the following is NOT a requirement for a good battery?
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What is the effect of dilution on the molar conductivity of a weak electrolyte?
What is the effect of dilution on the molar conductivity of a weak electrolyte?
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Which of these is NOT a characteristic of a strong electrolyte?
Which of these is NOT a characteristic of a strong electrolyte?
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Which of the following factors does not affect the electrode potential?
Which of the following factors does not affect the electrode potential?
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Which of the following statements is incorrect about the Nernst equation?
Which of the following statements is incorrect about the Nernst equation?
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Which of the following statements is true about the relationship between E°cell and the equilibrium constant (K)?
Which of the following statements is true about the relationship between E°cell and the equilibrium constant (K)?
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What is the electrode potential of a copper electrode immersed in a solution of 0.1 M Cu2+ ions at 25°C? (Given E°Cu2+/Cu = 0.34 V).
What is the electrode potential of a copper electrode immersed in a solution of 0.1 M Cu2+ ions at 25°C? (Given E°Cu2+/Cu = 0.34 V).
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In the electrochemical series, which of these metals will be the most reactive?
In the electrochemical series, which of these metals will be the most reactive?
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Which of the following statements is true about the relationship between E°cell and free energy (ΔG°)?
Which of the following statements is true about the relationship between E°cell and free energy (ΔG°)?
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What is the standard electrode potential (E°) for the hydrogen electrode?
What is the standard electrode potential (E°) for the hydrogen electrode?
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If the concentration of the metal ions in the electrolyte solution is increased, what will happen to the electrode potential?
If the concentration of the metal ions in the electrolyte solution is increased, what will happen to the electrode potential?
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What is the relationship between equivalent conductivity and molar conductivity?
What is the relationship between equivalent conductivity and molar conductivity?
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What is the unit of specific conductance?
What is the unit of specific conductance?
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What is the effect of dilution on the equivalent conductivity of strong electrolytes?
What is the effect of dilution on the equivalent conductivity of strong electrolytes?
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What is the cell constant of a conductivity cell?
What is the cell constant of a conductivity cell?
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What is the effect of dilution on the specific conductance of an electrolytic solution?
What is the effect of dilution on the specific conductance of an electrolytic solution?
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If the equivalent conductivity of a solution is 150 Ω-1 cm2 eq-1 and the molar conductivity is 75 Ω-1 cm2 mol-1, what is the valency of the metal ion in the electrolyte?
If the equivalent conductivity of a solution is 150 Ω-1 cm2 eq-1 and the molar conductivity is 75 Ω-1 cm2 mol-1, what is the valency of the metal ion in the electrolyte?
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How do you determine the cell constant of a conductivity cell?
How do you determine the cell constant of a conductivity cell?
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What is the difference between specific conductance and equivalent conductivity?
What is the difference between specific conductance and equivalent conductivity?
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What is the function of a salt bridge in a galvanic cell?
What is the function of a salt bridge in a galvanic cell?
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What is the correct representation of a galvanic cell?
What is the correct representation of a galvanic cell?
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What is the standard electrode potential (E°) of a half-cell?
What is the standard electrode potential (E°) of a half-cell?
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What does a positive value of E°cell indicate?
What does a positive value of E°cell indicate?
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Which of the following inert electrolytes is commonly used in a salt bridge?
Which of the following inert electrolytes is commonly used in a salt bridge?
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Which of the following is NOT a characteristic of the standard hydrogen electrode (SHE)?
Which of the following is NOT a characteristic of the standard hydrogen electrode (SHE)?
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What is the relationship between the electrode potential and the tendency of a metal to lose electrons?
What is the relationship between the electrode potential and the tendency of a metal to lose electrons?
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In a galvanic cell consisting of a zinc electrode and a copper electrode, which metal acts as the anode?
In a galvanic cell consisting of a zinc electrode and a copper electrode, which metal acts as the anode?
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Which of the following is the electrolyte used in a Mercury Cell?
Which of the following is the electrolyte used in a Mercury Cell?
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In a Leclanche Cell, the anode consists of:
In a Leclanche Cell, the anode consists of:
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What is the primary function of the PbO2 grid in a Lead Storage Battery?
What is the primary function of the PbO2 grid in a Lead Storage Battery?
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Which of the following statements is true regarding the Lead Storage Battery?
Which of the following statements is true regarding the Lead Storage Battery?
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What is a key characteristic of a primary cell?
What is a key characteristic of a primary cell?
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What is the chemical reaction that occurs at the cathode of a Mercury Cell during discharge?
What is the chemical reaction that occurs at the cathode of a Mercury Cell during discharge?
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Which of the listed cells are commonly used in watches and calculators?
Which of the listed cells are commonly used in watches and calculators?
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What is the fundamental difference between primary cells and secondary cells?
What is the fundamental difference between primary cells and secondary cells?
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Study Notes
Electrochemistry
- Electrochemistry is the study of processes involving the interconversion of electrical and chemical energy.
- Electrolysis is the decomposition of an electrolyte by an electric current. Positive ions are attracted by the cathode and negative ions are attracted to the anode. This involves oxidation at the anode and reduction at the cathode which depends on electron transfer at the electrodes.
Faraday's Laws of Electrolysis
- Faraday's First Law states the amount of substance deposited or evolved at an electrode is proportional to the quantity of electricity passed. W = ZIt
- Faraday's Second Law explains that the weights of different substances evolved/deposited are proportional to their chemical equivalents when the same quantity of electricity passes through different electrolytes. W1/E1 = W2/E2
Electrochemical Cells
- Galvanic/Voltaic cells produce electric current from spontaneous chemical reactions.
- Single electrode potentials signify the tendency of metals to become positively or negatively charged when placed in contact with their ions.
- Standard hydrogen electrode (SHE) is used as a reference. It is assigned a potential of zero under standard conditions. Measurement of standard electrode potential of other half-cells can be done using SHE.
- Factors like temperature and concentration affect electrode potential.
- The Nernst equation is applicable to correlation of free energy and cell emf.
- Electrochemical series is used to predict the spontaneity of a reaction.
Conductance
- Metallic Conductors: The movement of electrons results in no change to the overall chemical properties. Resistance increases with temperature and follows Ohm's law.
- Electrolyte Conductance: The movement of ions results in chemical changes. Resistance decreases with temperature and does not follow Ohm's law. Factors affecting electrolytic conduction include solute-solute interaction, solute-solvent interaction, temperature, viscosity, size of ions.
Specific, Equivalent, and Molar Conductance
- Specific Conductance (conductivity): The reciprocal of specific resistance (K=1/ρ), represented by unit Ω⁻¹ cm⁻¹.
- Equivalent Conductance( ^ eq): The conductivity of a solution containing 1 g equivalent of the solute when placed between two electrodes 1 cm apart. ^eq = Kx 1000/C
- Molar Conductance ( A m): The conductivity of a solution containing 1 mole of the solute when placed between two parallel electrodes of 1 cm apart. A m = x1000/M
Variation with Dilution
- Specific conductance decreases, as the number of ions per unit area decreases with dilution.
- Equivalent conductance and molar conductance of an electrolyte increases with dilution, but strongly electrolytes increases only slightly
- For strong electrolytes, molar conductivity approaches a constant maximum value as dilution approaches infinity.
- For weak electrolytes, molar conductivity approaches a constant value as dilution approaches infinity. This value cannot be obtained by extrapolating the curve.
Electrodes
- Standard Hydrogen Electrode (SHE) is the standard reference
- Calomel electrode and Weston cell are other electrodes used as reference electrodes.
Electrode Potentials
- Standard electrode potentials (E°) are measured under standard conditions.
- The higher the reduction potential value, the more likely an electrode is to undergo reduction.
- Nernst equation describes how electrode potential varies with concentration.
Galvanic Cells
- Diagram explanations of Zn/Cu galvanic cells and relevant electrochemical reactions.
- Salt bridges explanations in Galvanic cells
- Functions of salt bridge: Completing the circuit, maintaining electrical neutrality, preventing the mixing of electrolytes
Batteries
- Primary cells are not rechargeable (e.g., Leclanche cell, mercury cell)
- Secondary cells are rechargeable (e.g., Lead storage battery)
Fuel Cells
- Electro-chemical cells that require a continuous supply of reactants to keep functioning.
- Fuel cells are pollution free.
Corrosion
- Corrosion is the slow conversion of a metal to undesirable compounds, by reaction with moisture and other gases.
- Factors affecting corrosion: Reactivity of the metal, presence of moisture and air, presence of electrolytes (ions).
- Mechanism of corrosion: involves oxidation at the anode and reduction at the cathode.
- Prevention of corrosion: includes barrier protection (painting, oil/grease coatings, electroplating), sacrificial protection (using more reactive metals), and using antirust solutions.
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Description
Test your knowledge on key concepts of electrochemistry, including fuel cells, corrosion, and electrolyte behavior. This quiz covers essential topics such as the advantages of fuel cells, the role of electrolytes, and fundamental chemical reactions involved in these processes.
