Chapter U6, Problem 6STP

Interpretation Introduction

Interpretation:

The correct representation of a reaction under chemical equilibrium needs to be determined.

Concept introduction:

A chemical equilibrium is defined as a state of a chemical reaction where the concentrations of the reactants and the products do not change further with time. A chemical equilibrium is actually a dynamic equilibrium where the reactants and the products continuously inter-convert into one another, but their concentrations do not change over time.

A reversible reaction is defined as a reaction where the reactants convert into products over time. The products formed react among themselves to give back the reactants. The conversion of the reactants to the products is the forward reaction while the re-conversion of the products to the reactants is the reverse reaction. The forwards and the reverse reactions are in chemical equilibrium with each other.

Answer to Problem 6STP

Option (B) is the correct answer.

Explanation of Solution

Reason for Correct Option:

CO₂ binds with hemoglobin, Hb in blood in a reversible manner to form [CO₂: hemoglobin]. Since the reaction is reversible, hence, there must be two components to this reversible reaction − the forward reaction and the reverse reaction.

The forward reaction is the binding of CO₂ to hemoglobin to form [CO₂: hemoglobin] while the reverse reaction is the breakdown of [CO₂: hemoglobin] to CO₂ and hemoglobin. Since in a chemical equilibrium, the forward arrow points from the reactants to the products and the reverse arrow points in the opposite direction, option (B) is the correct representation.

Conclusion

Reasons for Incorrect Options:

The first option, (A) and (D) are incorrect because the question deals with the reversible binding of CO₂ with hemoglobin to form [CO₂: hemoglobin] and thus, the forward reaction must represent this combination. However, here, the breakdown reaction is the forward reaction which is off course, wrong as per the question.

The third option, (C) is incorrect because the reaction is irreversible, i.e, the breakdown of [CO₂: hemoglobin] to CO₂ and hemoglobin doesn’t occur which is incorrect.