Question

A state of equilibrium is reached when:

• A. the rate of forward reaction is greater is greater than the rate of the reverse reaction
• B. the concentration of the products and reactants are equal
• C. more products is presents than reactant
• D. the concentration of the products and reactants have reached constant value

Answer 1

The correct option is D the concentration of the products and reactants have reached constant value

At equilibrium state

$A\rightleftharpoons B$

Rate of forward Reaction= $K_f\left[A\right]$

Rate of backward Reaction= $K_b\left[B\right]$

At Equilibrium Rate of forward Reaction become equal to the rate of backward Reaction.

Thus, $K_f\left[A\right]=K_b\left[B\right]$

$\Rightarrow \frac{K_f}{K_b}=\frac{\left[B\right]}{\left[A\right]}$

$\Rightarrow K_{eq}=\frac{\left[B\right]}{\left[A\right]}$ $[where{K}_{eq}=\frac{K_f}{K_b}]$

$\Downarrow$

( which is constant )

Thus, the concentration of reactant and product become constant at equilibrium.