In the equilibrium constant expression Kc, what is the unit for Kc if the reacti

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Question: In the equilibrium constant expression Kc, what is the unit for Kc if the reaction is A(g) + B(g) ⇌ C(g)?

Options:

Correct Answer: dimensionless

Solution:

The equilibrium constant Kc is dimensionless because it is a ratio of concentrations raised to their stoichiometric coefficients.

In the equilibrium constant expression Kc, what is the unit for Kc if the reaction is A(g) + B(g) ⇌ C(g)?

In the equilibrium constant expression Kc, what is the unit for Kc if the reaction is A(g) + B(g) ⇌ C(g)?

Step 1: Identify the reaction: A(g) + B(g) ⇌ C(g).
Step 2: Write the expression for the equilibrium constant Kc: Kc = [C] / ([A] * [B]).
Step 3: Understand that [A], [B], and [C] represent the concentrations of the gases A, B, and C, respectively.
Step 4: Note that concentrations are measured in moles per liter (mol/L).
Step 5: Substitute the units into the Kc expression: Kc = (mol/L) / ((mol/L) * (mol/L)).
Step 6: Simplify the units: Kc = (mol/L) / (mol^2/L^2) = (mol/L) * (L^2/mol^2) = L/mol.
Step 7: Realize that the units cancel out, leading to a dimensionless quantity.
Step 8: Conclude that Kc is dimensionless.

Equilibrium Constant Expression – The equilibrium constant Kc is derived from the concentrations of reactants and products at equilibrium, raised to the power of their respective stoichiometric coefficients.
Units of Concentration – Concentration is typically expressed in molarity (mol/L), and the units can cancel out in the Kc expression.
Dimensionless Quantities – Kc is considered dimensionless because it represents a ratio of concentrations, which can lead to confusion regarding its units.