Lesson Worksheet: Primary Galvanic Cells Chemistry

In this worksheet, we will practice describing primary cells and explain how they produce electrical energy.


Which of the following reactions is the half-equation for the reaction that occurs at the cathode in a mercury cell?

  • AHgO+HO+2eHg+2OH2
  • BHg(OH)HgO+2OH+HO422
  • CHg+4OHHg(OH)+2e42
  • DZn+HgOZnO+Hg
  • EHg+2OHHgO+HO+2e2


The following diagram is a representation of a hydrogen fuel cell.

Considering the direction of electrons through the top circuit, shown by the red arrow, what gas is introduced through pipe A?

  • AHydrogen
  • BOxygen
  • CSteam


In hydrogen fuel cells, an electrical charge can be generated continuously.

What type of cell would a hydrogen fuel cell be classified as?

  • AA voltaic cell
  • BAn electrolytic cell

Why does a fuel cell not discharge and run out like disposable cells, such as the mercury cell?

  • AThe fuel cells are very efficient to run in most devices.
  • BThe water that is produced is broken down and reused.
  • CIt has a continuous supply of fuel.
  • DThe fuel cell is recharged by the device while it is running.
  • EUnreacted hydrogen and oxygen are recycled.


The overall voltage for a mercury cell is found to be +1.35 V. Consider the following electrode potential: HgO()+HO()+2eHg()+2OH()Vsllaq2𝐸=+0.0977

What must the reduction potential of the other electrode in the cell be? Give your answer to 4 decimal places.


A hydrogen fuel cell under acidic conditions has a standard cell potential of +1.23 V.

Consider the following half-equation reaction:


Given that the electrode potential of the cathode is also +1.23 V, what is the electrode potential of the anode where this half-equation reaction takes place?

What is this value of the electrode potential of the anode equivalent to?

  • AHalf of the electrode potential of the cathode
  • BThe electrode potential of the standard hydrogen electrode
  • CThe electrode potential of the cathode
  • DThe opposite polarity of the electrode potential of the cathode
  • EThe opposite polarity and half the electrode potential of the cathode


The two reduction half-equations for a hydrogen cell under alkaline conditions are as follows:


What is the overall cell potential, 𝐸cell, of this hydrogen cell?


A hydrogen fuel cell can operate under certain conditions, but the overall reaction of hydrogen combining with oxygen to form water is the same regardless.

Consider the following equations:

  1. 12O+HO+2e2OH22
  2. H()2H()+2e2+gaq
  3. 12O+2H+2eHO()2+2l
  4. H+2OH2HO+2e22

Which of the equations can be paired so that when they are combined they give the overall reaction for a hydrogen fuel cell?

  • AAD and BC
  • BAC and BD
  • CAB and CD


The illustration shows a representation of the inside of a hydrogen fuel cell.

What chemical is used for the central electrolyte?

  • APure water
  • BHydrogen peroxide
  • CDilute sulfuric acid
  • DPotassium hydroxide
  • EDeionized water

What are the two electrodes used in many hydrogen fuel cells made of?

  • ALithium
  • BPlatinum
  • CSteel
  • DCopper
  • ECeramic

What waste chemical is emitted at the anode?

  • AHO()2g
  • BCO()2g
  • CHO()22l
  • DH()2g
  • EOH()aq


A cross section of a mercury button cell is shown in the illustration.

What is the polarity of the anode? What is the material often used for it?

  • APositive, steel
  • BPositive, graphite
  • CPositive, cadmium
  • DNegative, zinc
  • ENegative, mercury

What chemical can act as an electrolyte in these types of cells and would be found saturated throughout the separator Q?

  • AZinc oxide
  • BPotassium hydroxide
  • CMercury metal
  • DMercuric oxide
  • EHydrochloric acid


A fuel cell is a primary galvanic cell that is mainly used to produce .

  • Aelectricity
  • Bwater
  • Cfuel
  • Doxygen

This lesson includes 19 additional questions for subscribers.

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