Use the chemical equation showing the dissolution of sodium bromide in water to answer the question.

Question

NaBr(s) ⇌ Na (aq) + Br (aq)
A student adds hydrobromic acid (HBr) to a solution of sodium bromide at equilibrium. How does this change affect the system?
(1 point)
+ −
The hydrogen ions bind to the dissolved bromine ions, and the equilibrium shifts to the products.
The additional bromine ions cause the equilibrium to shift to the reactants.
The additional bromine ions cause the equilibrium to shift to the products.
The hydrogen ions bind to the dissolved sodium ions and the equilibrium shifts to the reactants.

Answer 1

To understand how the addition of hydrobromic acid (HBr) affects the equilibrium of the dissolution of sodium bromide (NaBr) in water, we need to consider the components of HBr. Hydrobromic acid dissociates completely in water to produce hydrogen ions (H⁺) and bromide ions (Br⁻):

HBr → H⁺ + Br⁻

When HBr is added to the solution, it increases the concentration of bromide ions (Br⁻) in the system. According to Le Chatelier's principle, if a stress (such as an increase in the concentration of a product) is applied to a system at equilibrium, the system will adjust to counteract that change.

In this case, the increase in Br⁻ ions will shift the equilibrium to the left, toward the reactants, in order to reduce the concentration of Br⁻ ions in the solution:

NaBr(s) ⇌ Na⁺(aq) + Br⁻(aq)

Thus, the correct interpretation of this addition is:

The additional bromine ions cause the equilibrium to shift to the reactants.