Initially, We Place 2 Mol Of A And 4 Mol Of B In A 0.5 L Fla

Initially We Place 2 Mol Of A And 4 Mol Of B In A 05 L Flask At

Determine the value of the equilibrium constant K for the reaction given, based on the initial quantities of reactants and the equilibrium concentration of product C.

Sample Paper For Above instruction

Introduction

The determination of the equilibrium constant (K) is fundamental in chemical thermodynamics, providing insights into the extent of reactions under specified conditions. This paper discusses the process of calculating K based on initial reactants and equilibrium data, illustrating with a specific problem where 2 mol of A and 4 mol of B are placed in a 0.5 L flask, and the equilibrium concentration of C is 0.3 mol.

Calculating the Equilibrium Constant (K)

In the scenario, initial moles of reactants A and B are 2 mol and 4 mol, respectively, placed in a 0.5 L flask. During the reaction, some amount of A and B reacts to form product C. At equilibrium, the amount of C is 0.3 mol. The key step is to establish the change in moles of reactants and products and then utilize the expression for the equilibrium constant, which for a general reaction:

aA + bB ⇌ cC

is expressed as:

K = [C]^c / ([A]^a * [B]^b)

where concentrations are molarity (mol/L).

Given the initial moles, the initial concentrations are:

- [A]_initial = 2 mol / 0.5 L = 4 M

- [B]_initial = 4 mol / 0.5 L = 8 M

At equilibrium:

- [C]_equilibrium = 0.3 mol / 0.5 L = 0.6 M

Assuming the stoichiometry of the reaction is 1:1:1 (which is typical unless specified otherwise), then:

- Moles of A reacted: x mol

- Moles of B reacted: x mol

Thus:

- Moles of A at equilibrium: 2 - x

- Moles of B at equilibrium: 4 - x

- Moles of C at equilibrium: x

From the data:

- x = 0.3 mol (since equilibrium concentration of C is 0.6 M, which corresponds to 0.3 mol in 0.5 L)

Therefore:

- [A] = (2 - 0.3) mol / 0.5 L = 1.7 mol / 0.5 L = 3.4 M

- [B] = (4 - 0.3) mol / 0.5 L = 3.7 mol / 0.5 L = 7.4 M

- [C] = 0.6 M (already calculated)

Applying the equilibrium expression:

K = [C] / ([A] [B]) = 0.6 / (3.4 7.4) ≈ 0.6 / 25.16 ≈ 0.0238

Conclusion

The equilibrium constant K for this reaction is approximately 0.024, indicating the reaction favors the reactants under these conditions. This calculation exemplifies how initial reactant quantities and equilibrium concentrations enable the determination of reaction dynamics.

References

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