The requirement that a reversible reaction be at equilibrium is that:

- the concentrations on the two sides of the arrow be equal
- the velocity for the forward reaction equal that of the reverse reaction
- there will be as many molecules of the substances on one side of the arrow as there are molecules of the substances on the other side
- the moles of products will equal the moles of reactants

The velocity for the forward reaction equal that of the reverse reaction.

- the velocity for the forward reaction equal that of the reverse reaction

Explanation:-

Equilibrium constant is defined as the ratio of concentration of product to the concentration of reactants each raised to the power their stoichiometric ratios. It is represented by the symbol 'K'. For the general equilibrium equation:

The expression for equilibrium constant is given as:

Characteristics of equilibrium reaction:

Chemical equilibrium are attained is closed system.

The macroscopic remains constant like: volume, pressure, energy etc.

Rate of forward reaction is equal to the rate of backward reaction. The concentration of the reactants and products remain constant.They are not always equal.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

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