In the reaction involving addition of Fe(s) in aquous HCl, work done is:

(a) zero

(b) infinity

(c)intrinsic

(d) extrinsic

In the reaction where solid iron (Fe) is added to aqueous hydrochloric acid (HCl), the work done can be understood in terms of the nature of the reaction and the system's energy changes. The correct answer to your question is (a) zero.

Understanding the Reaction

When iron reacts with hydrochloric acid, it undergoes a chemical reaction that produces iron(II) chloride (FeCl2) and hydrogen gas (H2). The balanced equation for this reaction is:

• Fe(s) + 2 HCl(aq) → FeCl2(aq) + H2(g)

In this scenario, we need to consider what is meant by "work done." In thermodynamics, work is typically associated with the movement of a system against an external pressure or force. For example, when a gas expands in a piston, it does work on the piston as it pushes against the atmospheric pressure.

Why is Work Done Zero?

In the case of the reaction between solid iron and hydrochloric acid, the following points clarify why the work done is zero:

• No Volume Change: The reaction occurs in a solution where the volume of the reactants and products does not significantly change. Since there is no expansion against an external pressure, no work is done.
• Constant Pressure System: The reaction takes place at constant atmospheric pressure, and since the solid iron does not expand or compress the surrounding medium, the work remains zero.
• Energy Changes: While energy is released in the form of heat (exothermic reaction), this does not equate to mechanical work being done on the surroundings.

Clarifying Other Options

Let’s briefly discuss why the other options are not applicable:

• Infinity: This option suggests an unbounded amount of work, which is not feasible in a chemical reaction where no physical displacement occurs.
• Intrinsic: This term typically relates to properties inherent to a system, but it does not apply to the concept of work done in this context.
• Extrinsic: Similar to intrinsic, this term refers to external factors. However, in this reaction, there are no external forces doing work on the system.

Conclusion

In summary, when solid iron reacts with hydrochloric acid, the work done is zero due to the lack of volume change and the absence of mechanical displacement against external pressure. Understanding these principles helps clarify the thermodynamic behavior of chemical reactions.