Question

From the following list, identify those elements that are easier to oxidize than \(\mathrm{H}_{2}(\mathrm{g})\) (a) Cu (b) Zn (c) Fe (d) \(\mathrm{Ag}\) (e) \(\mathrm{Cr}\)

Short answer

Zn, Fe, and Cr are easier to oxidize than \\( H_{2}(g) \\).

Step-by-step solution

Understanding Oxidation Potential

To determine which elements are easier to oxidize than \(H_{2}(g)\), you need to consult the electrochemical series, which lists elements by their standard electrode potentials. The more negative the standard electrode potential, the more easily the element is oxidized.

Comparing Standard Electrode Potentials

Look up the standard electrode potentials for the given elements and hydrogen. The standard electrode potential for \(H_{2}(g)\) is set at 0.00 V. Elements with potentials less than 0.00 V are easier to oxidize than hydrogen.

Consulting the Electrochemical Series

Looking up data from the series: - Cu has a potential of +0.34 V - Zn has a potential of -0.76 V - Fe has a potential of -0.44 V - Ag has a potential of +0.80 V - Cr has a potential of -0.74 V. This clearly shows that Zn, Fe, and Cr have negative potentials and are more easily oxidized than hydrogen.

Identifying Elements Easier to Oxidize than Hydrogen

Based on the electrochemical series data, we find that zinc (Zn), iron (Fe), and chromium (Cr) have standard electrode potentials less than that of hydrogen, indicating they are easier to oxidize than hydrogen.

Key concepts

Electrochemical Series

The electrochemical series is a useful tool for predicting how readily an element will undergo oxidation or reduction reactions. It is essentially a list of standard electrode potentials arranged in order, helping chemists understand the tendency of elements to gain or lose electrons.
Elements at the top of the series, with more positive potentials, are better at undergoing reduction. Elements towards the bottom have more negative potentials and are better at being oxidized.

• This concept helps in predicting the feasibility of a redox reaction.
• It provides insight into the stability of metal ions in solution.
• By consulting the electrochemical series, chemists can compare which reactions will occur spontaneously.

Using this series, we can determine that elements like zinc ( Zn eq 0) oxidize easily compared to others like copper ( Cu eq 0) with higher potentials.

Standard Electrode Potential

The standard electrode potential is a measurement of the energetic tendency of a reduction half-reaction. It is denoted by the symbol E° eq . Each half-reaction has a particular E° eq value, measured in volts, determined under standard conditions.
For example, the standard electrode potential for hydrogen is standardized at 0.00 V. By comparing the potentials of other elements to hydrogen, chemists can predict their activity in electrochemical reactions.

• Elements with higher potentials ( E° eq >0.00 V) are more likely to gain electrons.
• Elements with lower potentials ( E° eq <0.00 V) tend to lose electrons easily and are good reducing agents.

This measurement is crucial for determining how a reaction proceeds and the likelihood of various reactions occurring.

Chemical Reactivity

Chemical reactivity refers to how readily an element or compound will react with other substances. It is influenced by various factors, including atomic structure, energy states, and electron affinities.
The electrochemical series provides vital insight into an element's reactivity, particularly with oxidation and reduction processes:

• An element's position in the series gives clues to its chemical behavior.
• More negative standard electrode potentials, as seen in elements like Zn , Fe , and Cr , suggest higher reactivity in terms of oxidation.
• Meanwhile, more positive potentials indicate a reduction preference, as seen in Ag and Cu .

Understanding these reactivity patterns helps chemists select appropriate materials for reactions and predict the paths of redox processes.

Oxidation-Reduction Reactions

Oxidation-reduction reactions, or redox reactions, are fundamental to the chemistry of metalloids and metals. These reactions involve the transfer of electrons between substances, where one species undergoes oxidation (loses electrons), and the other undergoes reduction (gains electrons).
In practical terms:

• Oxidation often increases an element's oxidation number.
• Reduction decreases the oxidation number.
• These reactions can be identified by changes in the color, energy state, or physical properties of the elements involved.

Understanding redox reactions allows chemists to harness electrical energy, design batteries, and clean up pollution, among other applications. Knowing which substances oxidize more easily, as seen with the standard potentials from the electrochemical series, is key in predicting and balancing these chemical processes.