Question

Which half reaction would more likely be an oxidation reaction: one with a standard reduction potential of \(-0.42 \mathrm{V},\) or one with a standard reduction potential of \(+0.42 \mathrm{V}\) ?

Short answer

\( -0.42 \, \mathrm{V} \)

Step-by-step solution

Understanding Standard Reduction Potential

Reduction potential indicates how likely a species is to gain electrons (be reduced). A higher reduction potential means a greater tendency to be reduced.

Compare Standard Reduction Potentials

Compare the given standard reduction potentials: - \( -0.42 \, \mathrm{V} \)- \( +0.42 \, \mathrm{V} \)

Determine Likely Reduction Reaction

The half-reaction with the higher standard reduction potential \( +0.42 \, \mathrm{V} \) is more likely to undergo reduction.

Determine Likely Oxidation Reaction

Since oxidation and reduction are opposite processes, the half-reaction with the lower reduction potential \( -0.42 \, \mathrm{V} \) is more likely to undergo oxidation.

Key concepts

Standard Reduction Potential

Standard reduction potential is a measure of the tendency of a chemical species to gain electrons and be reduced. It is denoted by the symbol E°. This potential is measured under standard conditions: 1 M concentration for solutions, 1 atm pressure for gases, and a temperature of 25°C. A higher positive E° value means the substance has a higher tendency to gain electrons and be reduced.

Conversely, a negative E° value indicates a lower tendency to gain electrons. In simple terms, if you have a substance with a high standard reduction potential, it 'wants' those extra electrons more than a substance with a lower standard reduction potential. This concept is at the heart of predicting chemical behavior in redox reactions.

Electrochemistry

Electrochemistry is the branch of chemistry that studies the relationship between electricity and chemical reactions. It's crucial in understanding how batteries work, how to perform electrolysis, and more.

Redox reactions are central to electrochemistry. These involve the transfer of electrons between chemical species. Here, there are two halves to the reaction: the oxidation half and the reduction half. Oxidation involves losing electrons, and reduction involves gaining electrons.

In any electrochemical cell, one half of the cell will undergo oxidation (losing electrons) and the other half will undergo reduction (gaining electrons). This electron flow between the two half-reactions generates electric current. Understanding electrochemistry enables us to harness this current for various purposes, such as powering electronic devices.

Half-Reactions

In redox reactions, we often break down the overall reaction into two simpler steps called half-reactions. Each half-reaction shows either the loss or gain of electrons.

One half-reaction will show the oxidation process, where a species loses electrons and therefore has an increase in oxidation state. The other half-reaction will depict the reduction process, where a species gains electrons and thus has a decrease in oxidation state.

Understanding half-reactions is crucial because it allows us to predict the nature of the substances involved—whether they are more likely to undergo reduction or oxidation.

In the exercise provided, we compared standard reduction potentials to determine which half-reaction is more likely to undergo oxidation or reduction. A half-reaction with a more positive standard reduction potential is more likely to be reduced, whereas one with a more negative standard reduction potential is more likely to be oxidized.