Which of the following, when added to an equilibrium mixture represented by the equlibrium below, will not alter the composition of the original equilibrium mixture? Mg (OH) 2 (s) Mg2 + (aq) + 2OH - (aq)

A. Addition of Mg (OH) 2 (s) to the equilibrium mixture.

B. Addition of HCl (aq) to the equilibrium mixture.

C. Addition of NaOH (s) to the equilibrium mixture.

D. Addition of Mg (NO3) 2 (s) to the equilibrium mixture.

E. Addition of Fe (NO3) 3 (aq) from the equilibrium mixture.

A. Addition of Mg (OH) 2 (s) to the equilibrium mixture.

Explanation:

A. Addition of Mg (OH) 2 (s) to the equilibrium mixture.

The equilibrium will not change because if more solid is added, it will occur in the same original equilibrium and also, there is no change in the equilibrium if the solid and liquid states of the species are changed because there concentration hardly changes as they are present in large amounts.

B. Addition of HCl (aq) to the equilibrium mixture.

HCl will furnish protons which will combine with the hydroxide ions and shifting the equilibrium in the forward direction.

C. Addition of NaOH (s) to the equilibrium mixture.

It will increase the hydroxide ion concentration and thus shifting equilibrium backward.

D. Addition of Mg (NO3) 2 (s) to the equilibrium mixture.

This will dissolve in the solution and furnish magnesium ions and thus shifting equilibrium backward.

E. Addition of Fe (NO3) 3 (aq) from the equilibrium mixture.

The ions it will form will form salts with their counter ions and thus changing the concentration of the products in the equilibrium.

Hence, A is the answer.