Question

Consider the reaction of water with ammonia: NH₃ + H₂O → NH₄⁺ + OH⁻. Which of the following statements best describes the concentration of ammonia and ammonium at equilibrium?

Select one:

a. Their concentrations are equal.

b. Their concentrations are constant.

c. There is no ammonia at equilibrium.

d. The concentration of ammonium is increasing.

e. There is no ammonium at equilibrium.

Answer 1

The concentration of ammonia and ammonium at equilibrium will be constant, but not necessarily equal, and this is because equilibrium allows for a consistent ratio as determined by the equilibrium constant. c. There is no ammonia at equilibrium.

Step-by-step explanation:

Considering the reaction between ammonia (NH3) and water (H2O) to produce ammonium (NH4+) and hydroxide (OH−), the concentration of ammonia and ammonium at equilibrium isn't necessarily equal. At equilibrium, the concentration of NH3 and NH4+ are constant, but their values depend on the equilibrium constant (K) for the reaction.

Increase in temperature usually shifts the position of equilibria according to Le Chatelier's Principle. If the reaction absorbs heat (endothermic), an increase in temperature will shift the equilibrium to favor the products. Conversely, if the reaction releases heat (exothermic), an increase in temperature will shift the equilibrium to favor the reactants. For the ammonia-water reaction, which is exothermic, raising the temperature would decrease the percent conversion of NH3 to NH4+.

Answer 2

The concentration of ammonia and ammonium at equilibrium is constant, not necessarily equal. Their specific concentrations depend on the equilibrium constant of the reaction, and these concentrations remain constant unless disturbed by changes such as temperature shifts. So, the correct option is b. Their concentrations are constant.

Step-by-step explanation:

When considering the reaction of water with ammonia, NH3 + H2O → NH4+ + OH−, at equilibrium, the concentration of ammonia (NH3) and ammonium (NH4+) depends on the equilibrium constant for this reaction. In general, for an equilibrium system, the concentrations of the reactants and products remain constant, but the actual values depend on the equilibrium constant and do not have to be equal.

Therefore, the statement that best describes the concentration of ammonia and ammonium at equilibrium is b. Their concentrations are constant. They are not necessarily equal, and the presence of both ammonia and ammonium ions in solution indicates that equilibrium has been established, with no component being completely converted into another.

When the temperature of the equilibrium system is increased, according to Le Châtelier's principle, the equilibrium will shift in the direction that absorbs the additional heat. If the reaction is exothermic, the equilibrium shifts towards the reactants, potentially lowering ammonia conversion to ammonium ion. If the reaction is endothermic, the equilibrium can shift towards the products, thus increasing the percentage of ammonia converted to ammonium ions.