chemical equilibrium constant的意思|示意

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Chemical equilibrium constant, also known as the equilibrium constant, is one of the most important concepts in chemistry. It is a numerical value that describes the relationship between the concentrations of the reactants and products of a reversible chemical reaction at equilibrium.

The chemical equilibrium constant (K) gives the ratio of the concentrations of the products (in their standard forms) to the concentrations of the reactants (in their standard forms). It is expressed as a dimensionless quantity and is written as:

K = [Products]/[Reactants]

When the equilibrium constant is greater than one, it means that products are in greater proportion and the reaction proceeds in the forward direction to form more products. When the equilibrium constant is less than one, it suggests that the reaction favors the formation of reactants and the reaction will proceed in the reverse direction to form more reactants.

K can also be used to calculate the concentrations of reactants and products at equilibrium. When the initial concentrations of the reactants and products are known, the concentrations at equilibrium can be solved from the equation:

K = [Products]/[Reactants]

For example, for the reaction A + B ⇌ 2C + D, if the initial concentrations are [A] = 0.006, [B] = 0.050 and [C] = 0.005, the equilibrium concentrations of the reactants and products can be solved by using the following equation:

At equilibrium, [C]2/[A][B] = K

Thus,

K = [C]2/[A][B]

= 0.005x0.005/0.006x0.050

= 0.041

and

[A] = 0.006/0.041

= 0.147

[B] = 0.050/0.041

= 1.22

[C] = 0.005 x 0.041

= 0.020

[D] = 0.020 x 0.041

= 0.008

The chemical equilibrium constant is a useful tool for chemists to predict the rate of reactions and the concentrations of reactants and products at equilibrium. It can also be used to analyze the effects of changing temperature, pressure, or concentration on the equilibrium of a reaction.