Question

Negative sign in the standard electrode potential indicates (a) greater ease of oxidation compared to that of hydrogen (b) greater ease of reduction compared to that of hydrogen (c) lesser ease of oxidation compared to that of hydrogen (d) none of the above

Short answer

Answer: Greater ease of oxidation compared to hydrogen.

Step-by-step solution

Understanding Standard Electrode Potentials

Standard electrode potentials, also known as reduction potentials, provide a measure of the tendency of a species (atoms, ions, or molecules) to lose or gain electrons and undergo reduction. Reduction is the process of gaining electrons, whereas oxidation is the process of losing electrons. The standard electrode potential is measured with reference to the hydrogen electrode, which is assigned a potential of 0 volts. If an electrode has a positive potential, it implies that the species is easier to reduce compared to hydrogen. On the other hand, if an electrode has a negative potential, it implies that the species is less likely to be reduced compared to hydrogen.

Initializing and Analyzing the Given Choices

Now that we understand standard electrode potentials, let's analyze the given choices: (a) greater ease of oxidation compared to that of hydrogen (b) greater ease of reduction compared to that of hydrogen (c) lesser ease of oxidation compared to that of hydrogen (d) none of the above The question is about a negative sign in the standard electrode potential. As we've learned earlier, a negative electrode potential implies that the species is less likely to be reduced as compared to hydrogen.

Selecting the Correct Option

When a species is less likely to be reduced (less likely to gain electrons), it means it has a greater ease of oxidizing (losing electrons) compared to hydrogen. That matches with option (a). Therefore, the correct choice is: (a) greater ease of oxidation compared to that of hydrogen

Key concepts

Oxidation and Reduction

In the realm of chemistry, the concepts of oxidation and reduction are two halves of a whole, referred to as redox reactions. These reactions involve the transfer of electrons between substances, significantly affecting the chemical properties of elements and compounds involved. Oxidation is characterized by the loss of electrons from a substance. When a species undergoes oxidation, it increases its oxidation number and becomes more positively charged.
Reduction, conversely, involves the gain of electrons, resulting in a decreased oxidation number and a more negatively charged species. To remember which is which, the acronym 'OIL RIG' can be helpful; it stands for 'Oxidation Is Loss, Reduction Is Gain' of electrons.
These processes are not solitary events; where there is oxidation, there is always a corresponding reduction. One classic example of a redox reaction is the rusting of iron, where iron oxidizes, and oxygen is reduced. Understanding these concepts is essential in solving problems related to standard electrode potentials as they define the direction in which the reaction moves—toward the gain or loss of electrons.

Hydrogen Electrode Reference

The hydrogen electrode serves as a standard reference point in electrochemistry and is essential for determining the standard electrode potential of other elements and compounds. It consists of a platinum electrode coated with platinum black, immersed in an acidic solution, and surrounded by hydrogen gas at standard conditions of temperature and pressure (25 degrees Celsius and 1 atmosphere, respectively).
By definition, the hydrogen electrode has an electrode potential of 0 volts. It works on the principle that hydrogen protons (H+) in solution gain electrons to form hydrogen gas (H₂), which is a reduction reaction. The standard hydrogen electrode (SHE) is used as a reference for ranking the reducing or oxidizing power of other substances. Substances with a negative standard electrode potential compared to hydrogen tend to lose electrons (oxidize) more readily than hydrogen. Conversely, those with a positive potential are more likely to gain electrons (reduce) than hydrogen. This simple baseline offers clarity and consistency across various chemical reactions and is pivotal in the field of electrochemistry.

Electrochemistry

Electrochemistry is the branch of chemistry that investigates the movement of electrons to generate electrical energy from chemical reactions and vice versa. It revolves primarily around redox reactions and the conversion between chemical energy and electrical energy. Electrochemical cells, including galvanic cells and electrolytic cells, are practical applications of electrochemical principles.
Understanding standard electrode potentials is fundamental in electrochemistry as it allows us to predict the spontaneity and direction of redox reactions. For example, when two dissimilar metals are submerged in an electrolyte solution and connected, a spontaneous redox reaction might occur, driving electrons from the anode to the cathode and generating electricity. Batteries, corrosion, and electrolysis are all everyday examples of electrochemical processes.
To convey this to students vividly, consider using real-life examples such as how batteries power devices or the electroplating of jewelry. This practical relatability can sometimes make abstract concepts like standard electrode potentials much easier to comprehend.