Question

6. 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(NO3)2(s) to the equilibrium mixture.

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

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

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

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

I was given an answer of Mg(OH)2 but that doesnt make any sense to me

Answer 1

A)

Mg(NO3)2(s) is soluble and it gives Mg2+

This is like adding product and hence effect equilibrium

B)

Fe(NO3)2 is soluble and it gives NO3-

This is like adding product and hence effect equilibrium

D)

HCl is acid and adding HCl will react with OH-

This is like removing OH-

This will effect equilibrium

E)

NaOH will give OH-

This is like adding product and hence effect equilibrium

Mg(OH)2 (s) is part of equilibrium. Adding more Mg(OH)2 will not disturb equilibrium as this is solid and adding solid that is part of equilibrium do not effect equilibrium

Answer: C