Electrolytic and Galvanic Cells Quiz
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Electrolytic and Galvanic Cells Quiz

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@GoodMilkyWay

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Questions and Answers

What is the primary role of the negative terminal in both electrolytic and galvanic cells?

  • It is the terminal that generates power.
  • It is the point of oxidation.
  • It is where reduction occurs. (correct)
  • It is where the electrolyte is introduced.

    • Which of the following statements about alkaline cells is NOT true?

  • They have a longer shelf life than Carbon-Zinc cells.
  • They produce gaseous products during operation. (correct)
  • They can be rechargeable.
  • They perform better under cold weather conditions.

    • What distinguishes secondary cells from primary cells?

  • Secondary cells can be restored to their original state by charging. (correct)
  • Secondary cells can only be used once.
  • Secondary cells cannot be restored after discharge.
  • Secondary cells operate solely on carbon-based electrolytes.

    • In the construction of lead-acid batteries, what is the purpose of the separators?

    <p>To hold plates apart while allowing electrolyte movement.</p> Signup and view all the answers

    Which of the following is a characteristic of alkaline cells?

    <p>They have a similar electrolyte to carbon-zinc cells.</p> Signup and view all the answers

    What unique feature do lead-acid batteries have in terms of plate configuration?

    <p>There is always one more negative plate than positive plates.</p> Signup and view all the answers

    Which of the following types of secondary cells is NOT commonly recognized?

    <p>Carbon-zinc</p> Signup and view all the answers

    What is the typical outcome of charging a secondary cell?

    <p>It restores the cell to its original condition.</p> Signup and view all the answers

    What occurs when a lead-acid battery is discharged significantly over time?

    <p>Sulphation occurs, causing capacity loss.</p> Signup and view all the answers

    During the charging process of a lead-acid battery, what happens to the sulphate on the plates?

    <p>It disassociates from lead and returns to the electrolyte.</p> Signup and view all the answers

    What is the approximate specific gravity of the electrolyte when the battery is fully charged?

    <p>1.270</p> Signup and view all the answers

    What is a critical effect of discharging a lead-acid battery below 10.5 volts?

    <p>It severely damages the battery.</p> Signup and view all the answers

    What is the role of vent plugs during the final charging phase?

    <p>To allow the escape of gases produced during decomposition.</p> Signup and view all the answers

    What happens to the internal resistance of a lead-acid battery?

    <p>It opposes current flow through the cell.</p> Signup and view all the answers

    What is necessary to prevent damage when charging a lead-acid battery?

    <p>Ensuring little or no sulphate is left on the plates.</p> Signup and view all the answers

    Which statement accurately reflects the chemical changes during charging in a lead-acid battery?

    <p>Sulphuric acid is generated from sulphate.</p> Signup and view all the answers

    How should a lead-acid battery be maintained while in service?

    <p>It needs periodic topping up with distilled water.</p> Signup and view all the answers

    What is the primary consequence of increased internal resistance in a lead-acid battery?

    <p>Limited battery output and performance.</p> Signup and view all the answers

    What is the key advantage of using series-parallel connected cells over single cells?

    <p>They provide a higher voltage and a higher current.</p> Signup and view all the answers

    What occurs during normal charging when a battery experiences gassing?

    <p>Violent gassing suggests the battery is overcharged.</p> Signup and view all the answers

    Which statement correctly describes the function of a hydrometer in the context of battery maintenance?

    <p>It checks the specific gravity of the electrolyte.</p> Signup and view all the answers

    What is the Seebeck effect in relation to thermocouples?

    <p>It explains the production of EMF from heat applied to dissimilar metals.</p> Signup and view all the answers

    How is the potential difference measured in a thermocouple?

    <p>Through the cold junction connected to a meter.</p> Signup and view all the answers

    What is the main purpose of the electrolyte in a cell?

    <p>To act upon the electrodes</p> Signup and view all the answers

    Which statement accurately describes a secondary cell?

    <p>It can be recharged multiple times.</p> Signup and view all the answers

    In series connections of batteries, which of the following is true?

    <p>Voltage increases while current remains constant.</p> Signup and view all the answers

    What is the primary consequence of using batteries in parallel?

    <p>Increased current supply</p> Signup and view all the answers

    What component typically serves as the negative terminal in a dry cell?

    <p>The Zinc container</p> Signup and view all the answers

    Which of the following substances is used to neutralize alkaline spills?

    <p>Boric acid solution</p> Signup and view all the answers

    What is a defining characteristic of dry cells compared to wet cells?

    <p>Dry cells use a paste instead of liquid electrolyte.</p> Signup and view all the answers

    What is NOT a function of the electrodes in a cell?

    <p>Providing a structural framework</p> Signup and view all the answers

    What is the significance of connecting cells in series-parallel configurations?

    <p>Increases both current and voltage</p> Signup and view all the answers

    Which of the following statements about primary cells is correct?

    <p>They are no longer functional once discharged.</p> Signup and view all the answers

    What is the primary characteristic of the internal resistance of a Nickel-Cadmium cell compared to a Lead-acid cell?

    <p>It remains constant until nearly all charge is depleted.</p> Signup and view all the answers

    Which electrolyte composition is used in Nickel-Cadmium cells?

    <p>Potassium Hydroxide and water (30% by weight)</p> Signup and view all the answers

    What happens to the negative terminal of a Nickel-Cadmium cell when it is discharged?

    <p>It becomes Cadmium Hydroxide.</p> Signup and view all the answers

    What is a notable benefit of using a Nickel-Cadmium cell at high discharge rates?

    <p>Greater power delivery capacity.</p> Signup and view all the answers

    Which statement accurately describes the state of the Nickel-Cadmium cell's electrolyte during the charging process?

    <p>It is only visible and checked at the end of the charge cycle.</p> Signup and view all the answers

    How does the charge retention capability of a Nickel-Cadmium cell compare to that of a Lead-acid cell?

    <p>Ni-Cad can maintain a full charge when stored longer.</p> Signup and view all the answers

    What potential danger arises from high charging cycles in Nickel-Cadmium cells?

    <p>Thermal runaway due to high temperatures.</p> Signup and view all the answers

    Which of the following statements is true regarding the maintenance of Nickel-Cadmium cells?

    <p>They need no maintenance related to electrolyte addition.</p> Signup and view all the answers

    What is the nominal open-circuit cell voltage for a Nickel-Cadmium cell?

    <p>1.3 volts</p> Signup and view all the answers

    What defines the effect of the age of the electrolyte in Nickel-Cadmium cells?

    <p>It typically increases with age.</p> Signup and view all the answers

    Study Notes

    Electrolytic and Galvanic Cells

    • Oxidation occurs at the positive terminal, which has a positive charge.
    • Reduction occurs at the negative terminal, which has a negative charge.

    Alkaline Cells

    • Similar to Carbon-Zinc cells, but use an alkali solution (Potassium Hydroxide) as the electrolyte.
    • Deliver sustained high currents.
    • More efficient than Carbon-Zinc cells.
    • Have a longer shelf life.
    • Perform better in cold weather and under drain.
    • Do not produce any gaseous products.
    • May be rechargeable.
    • Types: Mercury Oxide, Silver Oxide, Zinc-air.

    Secondary Cells

    • Electrodes and electrolyte are altered when the cell delivers current.
    • Can be restored to their original state by charging.
    • Charging involves an electric current passed through the cell in the opposite direction of discharge.
    • Sometimes known as wet cells.
    • Common example is an automobile battery.

    Some Basic Types of Secondary Cells

    • Lead-acid
    • Nickel-cadmium
    • Silver-Zinc
    • Silver-cadmium

    Lead-acid Battery Construction

    • Consists of 6 cells for a 12-volt battery or 12 cells for a 24-volt battery.
    • Containers are made from hard rubber, plastic, or other insulating material.
    • Resistant to electrolyte, mechanical shock, and extreme temperatures.
    • Vent plugs allow gases to escape.

    Lead-acid Battery Construction - Components

    • Separators hold plates apart while allowing the free movement of electrolyte.
    • Separator material includes wood, perforated glass, rubber, or plastic.
    • Bottom of the cell contains a space to collect sediment that forms during use.
    • There is always one more negative plate than positive plates.
    • All cells have an uneven number of plates, for example, a 9-plate cell has 5 negative and 4 positive plates.

    Lead-acid Battery Discharging

    • Sulphuric acid combines with the active material in both plates.
    • Forms "lead sulphate" on the plates and water (H2O) in the electrolyte.
    • Increases battery internal resistance and decreases electrolyte specific gravity (SG).
    • Completely discharged SG is 1.150.
    • If left discharged for a prolonged period, sulphation occurs, and the cells lose capacity.

    Lead-acid Battery Charging

    • Reverses the chemical action from discharging.
    • Sulphate on both the positive and negative plates disassociates from lead.
    • Sulphate returns to the electrolyte to form sulphuric acid (H2SO4).
    • Positive plate changes back to lead peroxide, and the negative plate changes back to spongy lead.
    • Specific gravity of the electrolyte rises to the charged value, approximately 1.270

    Lead-acid Battery Final Charging Phase

    • Little or no sulphate remains on the plates.
    • Charging current decomposes water into its hydrogen and oxygen components.
    • Gases are released through vent plugs; hydrogen gas is explosive.
    • Batteries in service need to be periodically topped up with distilled water.

    Lead-acid Battery Operation Review

    • Discharging a lead acid battery below 10.5 volts will severely damage it.

    Internal Resistance

    • Every cell has internal resistance.
    • Opposes current flow through the cell, limiting battery output.
    • Inversely proportional to the area of electrodes exposed to electrochemical action.
    • Directly proportional to the distance separating electrode surfaces.
    • Influenced by the nature and condition of the electrolyte, typically increasing with age.
    • Becomes part of the overall circuit resistance.

    Nickel-Cadmium Cells

    • Known as Ni-Cad, far superior to Lead-acid cells.
    • Require less maintenance regarding the addition of electrolyte or water.
    • Negative terminal is Cadmium.
    • Positive terminal is Nickel Oxide.
    • Electrolyte is Potassium Hydroxide and water (30% by weight).

    Nickel-Cadmium Cell: Discharging

    • When the cell is discharged:
    • Negative terminal becomes Cadmium Hydroxide.
    • Positive terminal becomes Nickel Hydroxide.

    Nickel-Cadmium Cell

    • Ni-Cad and Lead-acid cells have comparable capacities at normal discharge rates.
    • At high discharge rates, Ni-Cad cells can deliver more power.
    • Ni-Cad cells can:
      • Be charged in a shorter time.
      • Stay idle longer in any state of charge.
      • Keep a full charge when stored for a longer period.
      • Be charged and discharged any number of times without detriment.

    Nickel-Cadmium Cell

    • Nominal open-circuit cell voltage is 1.3 volts.
    • Significant advantage over Lead-acid is the very low internal resistance:
      • Voltage remains constant until almost totally discharged (70-80% of charge).
      • Allows high charging rates without damage.
    • High discharge and charging rates are favourable, but dangers are involved, particularly high battery temperatures.

    Nickel-Cadmium Cell: Thermal Runaway

    • High charge cycles produce high temperatures.

    Connecting cells

    • Batteries connected in series increase voltage but not current.
    • Batteries connected in parallel increase current but not voltage.
    • Batteries connected in series-parallel increase both current and voltage.

    Battery Questions

    • What is the purpose of a cell? A cell is a device that converts chemical energy to electrical energy.
    • What are the 3 parts of a cell? Electrodes, electrolyte, and container.
    • What is the purpose of each of the 3 parts of a cell?
      • Electrodes conduct current.
      • Electrolyte acts upon the electrodes.
      • Container holds the electrolyte and mounts the electrodes.
    • What is electrochemical action? The process of converting chemical energy into electrical energy.
    • What serves as the negative terminal of a dry cell? The Zinc container.
    • Why is a dry cell called a DRY cell? The electrolyte is not a liquid but is in the form of a paste.
    • What are the 2 types of cells? Primary and secondary.
    • What is the main difference between the 2 types of cells? Secondary cells can be restored to their original condition by an electric current, while primary cells cannot.
    • Can a battery be recharged by adding more electrolyte? No, a current must be passed through the battery.
    • What are the 3 ways of combining cells, and what is each used for?
      • Series: Increase voltage but not current.
      • Parallel: Increase current but not voltage.
      • Series-parallel: Increase both current and voltage.
    • What are some advantages of a Ni-Cad cell over a lead-acid cell?
      • Can deliver a larger amount of power.
      • Can be charged in a shorter time.
      • Stays idle longer in any state of charge.
      • Be charged and discharged any number of times without detriment.
    • What is used to neutralize (a) acid and (b) alkaline spills?
      • Acid: Bicarbonate of soda (baking soda) or ammonia.
      • Alkaline: Chromic acid solution on aircraft, 3% solution of boric acid or acetic acid (vinegar).

    Battery Summary

    • Capacity is an indication of a battery's current-supplying capability for a specific period, measured in ampere-hours.
    • Battery charge is the process of reversing current flow through the battery to restore it to its original condition.
    • Gassing is the production of hydrogen gas caused by the charge current breaking down the water in the electrolyte.
    • Steady gassing is normal during the charging process. Violent gassing indicates that the charge rate is too high.

    Thermocouples

    • One of several devices for sensing temperature.
    • Typical uses in aircraft include:
      • Sensing cylinder head temperature on piston engines.
      • Sensing the temperature of gas passing into, through, or from turbines (gas turbine engines).
      • Some older aircraft use them as fire warning detectors, sensing abnormally rapid temperature increases.

    Thermocouple Operation

    • The production of EMF by heat is generated by applying heat to a junction formed by two dissimilar metals.
    • The joined metal junction is the hot junction.
    • The unjoined section is the cold junction.
    • Applying heat to the metals results in freeing electrons.
    • The energy required to free electrons differs for each metal, resulting in a varying charge.
    • The potential difference between the metals can be measured at the cold junction.
    • The phenomenon of producing a potential via heat is called the Seebeck effect.
    • The combination of the junction and the two dissimilar metals is known as a thermocouple.

    Thermocouple Operation

    • The hot junction is connected to a meter calibrated in degrees Celsius.
    • The meter effectively forms the cold junction.

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    Description

    Test your knowledge on electrolytic and galvanic cells, including their processes of oxidation and reduction. Delve into the specifics of alkaline cells and secondary cells, exploring their properties, types, and applications. This quiz will cover essential concepts to help you understand various types of electrochemical cells.

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