Question

The equation below shows the reaction of zinc with hydrochloric acid (HCl).

Zn (s) + 2 HCl (aq) —> ZnCl2 (aq) + H2 (g)

What will happen if the concentration of HCl is decreased?

A. More ZnCl2 will be produced.
B. The reaction rate will slow down.
C. The hydrochloric acid will become more acidic.
D. The reaction will produce water instead of hydrogen gas.

Answer 1

Zn(s) + 2HCl (aq) -----> ZnCl​​​2 (aq) + H​​​​​​2 (g)

Here rate of reaction depends upon twice of the concentration of HCl.

Thus if concentration of HCl is lowered, rate of the reaction will be lowered and less ZnCl​2 will be produced.

Thus answer is (B) The reaction will be slow down.

Answer 2

Step-by-step explanation:

Zn + 2HCl ⇄ ZnCl₂ + H₂

A system in equilibrium will try to annul any stress placed on the system for it to maintain the equilibrium position.

For reactions in which concentration changes are effected, the equilibrium shifts to the right if the concentration of species on the reactant side is increased and vice versa.

In the reaction above, if the concentration of the HCl is decreased, the equilibrium will shift to the left in order to increase back the concentration of both the Zn and HCl. Therefore, the acid HCl will become more acidic.