Consider the following equilibrium reaction having gaseous reactants and products.

4HCl + O2 ⇌ 2H2O + Cl2

Which of the following would result from increasing the volume of water vapors?

The volume of hydrochloric acid increases.

The rate of backward reaction decreases.

The rate of forward reaction increases.

The volume of chlorine increases.

The volume of water vapor decreases.

Explanation:

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The volume of hydrochloric acid increases.

Explanation:

Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

Increasing the volume of water vapors:

will increase the the concentration of the products side, so the reaction will be shifted to the left side (backward) to suppress the increase in the concentration of water vapors by addition.

So, The volume of hydrochloric acid increases, the rate of backward reaction increases, the rate of forward reaction decreases, and the volume of chlorine decreases.

So, the right choice is: The volume of hydrochloric acid increases.