Question 1

Which of the following statements best describes the function of the standard hydrogen electrode (SHE) in measuring standard reduction potentials?

Accepted Answer

It provides a reference point with a defined potential of $$0\ \mathrm{V}$$, allowing comparison of other half-cells.

Question 2

A galvanic cell is constructed using a zinc electrode in $$1\ \mathrm{M}\ \mathrm{Zn}^{2+}$$ and a copper electrode in $$1\ \mathrm{M}\ \mathrm{Cu}^{2+}. $$Given $$E^\circ_{\mathrm{red}}(\mathrm{Cu}^{2+}/\mathrm{Cu}) = 0.34\ \mathrm{V}$$ and $$E^\circ_{\mathrm{red}}(\mathrm{Zn}^{2+}/\mathrm{Zn}) = -0.76\ \mathrm{V}$$, what is the standard cell potential ($$E^\circ_{\mathrm{cell}}$$)?

Accepted Answer

$$E^\circ_{\mathrm{cell}} = 0.34\ \mathrm{V} - (-0.76\ \mathrm{V}) = 1.10\ \mathrm{V}$$

Question 3

In a galvanic cell, which of the following statements is TRUE regarding the flow of electrons?

Accepted Answer

Electrons flow from the anode (where oxidation occurs) to the cathode (where reduction occurs).

Question 4

Which of the following acids is classified as a non-oxidising acid under standard conditions?

Accepted Answer

Cold, dilute $$\mathrm{H}_2\mathrm{SO}_4$$

Question 5

A student sets up a galvanic cell with a standard hydrogen electrode and a copper electrode. The measured cell voltage is $$+0.34\ \mathrm{V}. $$What does this indicate about the relative reduction potentials and the direction of electron flow?

Accepted Answer

The copper half-cell has a higher reduction potential than the SHE, and electrons flow from hydrogen to copper.

Question 6

Which of the following best explains why concentrated $$\mathrm{H}_2\mathrm{SO}_4$$ can act as an oxidising acid, while dilute $$\mathrm{H}_2\mathrm{SO}_4$$ cannot?

Accepted Answer

The sulfate ion acts as a stronger oxidising agent in concentrated, hot conditions, allowing it to accept electrons from metals.

Question 7

Given the following half-reactions and their standard reduction potentials:

$$\mathrm{Ag}^+ (aq) + e^- \rightarrow \mathrm{Ag} (s)\ \ \ \ E^\circ_{\mathrm{red}} = 0.80\ \mathrm{V}$$

$$\mathrm{Fe}^{2+} (aq) + 2e^- \rightarrow \mathrm{Fe} (s)\ \ \ \ E^\circ_{\mathrm{red}} = -0.44\ \mathrm{V}$$

Which species will be reduced and which will be oxidised in a galvanic cell constructed from these two half-cells?

Accepted Answer

$$\mathrm{Ag}^+$$ will be reduced and $$\mathrm{Fe}$$ will be oxidised.

Question 8

A potato battery is constructed using a zinc electrode and a copper electrode. If the theoretical cell potential is $$1.10\ \mathrm{V}$$ but the measured voltage is $$0.40\ \mathrm{V}$$, what is the most likely reason for the difference?

Accepted Answer

The potato introduces internal resistance and possible side reactions, reducing the observed voltage.

Question 9

Which of the following statements about standard reduction potentials is CORRECT?

Accepted Answer

A more positive standard reduction potential means the species is a stronger oxidising agent.

Question 10

Consider the following redox reaction:

$$\mathrm{Zn} (s) + 2\mathrm{H}^+ (aq) \rightarrow \mathrm{Zn}^{2+} (aq) + \mathrm{H}_2 (g)$$

Given $$E^\circ_{\mathrm{red}}(\mathrm{Zn}^{2+}/\mathrm{Zn}) = -0.76\ \mathrm{V}$$ and $$E^\circ_{\mathrm{red}}(\mathrm{H}^+/\mathrm{H}_2) = 0.00\ \mathrm{V}$$, will this reaction proceed spontaneously under standard conditions?

Accepted Answer

Yes, because $$E^\circ_{\mathrm{cell}} = 0.00\ \mathrm{V} - (-0.76\ \mathrm{V}) = 0.76\ \mathrm{V}$$, which is positive.

Question 11

Which of the following best describes the role of the salt bridge in a galvanic cell?

Accepted Answer

It maintains electrical neutrality by allowing the flow of ions between the half-cells.

Question 12

A student wants to construct a galvanic cell that produces the highest possible voltage using two metals from the reduction potential table. Which combination should they choose?

Accepted Answer

Select one metal with the most positive and one with the most negative standard reduction potential.

Question 13

Which of the following is a correct statement about writing spontaneous redox reactions using standard reduction potentials?

Accepted Answer

The reactants should include the stronger oxidising agent and the stronger reducing agent.

Question 14

A galvanic cell is constructed with a magnesium electrode ($$E^\circ_{\mathrm{red}} = -2.37\ \mathrm{V}) $$and a silver electrode ($$E^\circ_{\mathrm{red}} = 0.80\ \mathrm{V}). $$What is the standard cell potential, and which metal is oxidised?

Accepted Answer

$$E^\circ_{\mathrm{cell}} = 0.80\ \mathrm{V} - (-2.37\ \mathrm{V}) = 3.17\ \mathrm{V}$$; magnesium is oxidised.

Question 15

Which of the following best explains why nitric acid ($$\mathrm{HNO}_3) is $$considered an oxidising acid?

Accepted Answer

Its anion ($$\mathrm{NO}_3^-) $$has a higher reduction potential than $$\mathrm{H}^+$$, making it a stronger oxidising agent.

Question 16

A reaction is proposed: $$\mathrm{Cu} (s) + 2\mathrm{H}^+ (aq) \rightarrow \mathrm{Cu}^{2+} (aq) + \mathrm{H}_2 (g). $$Given $$E^\circ_{\mathrm{red}}(\mathrm{Cu}^{2+}/\mathrm{Cu}) = 0.34\ \mathrm{V}$$ and $$E^\circ_{\mathrm{red}}(\mathrm{H}^+/\mathrm{H}_2) = 0.00\ \mathrm{V}$$, will this reaction proceed spontaneously?

Accepted Answer

No, because $$E^\circ_{\mathrm{cell}} = 0.00\ \mathrm{V} - 0.34\ \mathrm{V} = -0.34\ \mathrm{V}$$, which is negative.

Question 17

In the context of a potato battery, what is the primary role of the potato?

Accepted Answer

It serves as an electrolyte, allowing ion flow between the electrodes.

Electrochemistry: Reduction Potentials, Galvanic Cells, and Applications

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