1. what is law of mass action?

2.Explain law of chemical equilibrium and derive it.

**1)Law of Mass action :**This law was given by Guldberg and Waage in 1864. It states that- The rate of reaction is proportional to the product of the active masses of the reactants , each raised to the power to its stoichiometric coefficient as represented by the balanced reaction.

2)

**Law of chemical equilibrium**: It states that- The product of the molar concentration of the products, each raised to the power equal to its stoichiometric coefficient divided by the product of the molar concentrations of the reactants , each raised to the power equal to its stoichiometric coefficient is constant at constant temperature and is called Equilibrium constant.

__DERIVATION:__

consider the general reversible reaction:

A + B $\leftrightarrow $ C + D

At equilibrium , suppose the active masses of A, B, C, and D are represented as [A], [B], [C] and [D].

Applying the law of mass action-

Rate at which A and B react together , that is , Rate of forward reaction $\alpha $ [A][B]

= K

_{f}

_{ }[A][B]

where K

_{f}is proportionality constant is called as velocity constant for forward reaction.

Similarly, rate at which C and D react together ,that is, Rate of the backward reaction

= K

_{b}[C][D]

where K

_{b}represents the velocity constant for the backward reaction

At equilibrium,

Rate of forward reaction= Rate of the backward reaction

K

_{f}[A][B]= K

_{b}[C][D]

$\frac{{K}_{f}}{{K}_{b}}=\frac{\left[C\right]\left[D\right]}{\left[A\right]\left[B\right]}$

**K**= $\frac{\left[C\right]\left[D\right]}{\left[A\right]\left[B\right]}$

Where

**K is Equilibrium Constant**

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