A 0.10-mol sample of H2(g) and a 0.10-mol sample of Br2(g) are placed in a 2.0-L container. The reaction H2(g) + Br2(g) <----> 2 HBr(g) is then allowed to come to equilibrium. A 0.20 mol sample of HBr is placed into a second 2.0-L sealed container at the same temperature and allowed to reach equilibrium with H2 and Br2.
Which of the following will be different in the two containers at equilibrium? Which will be the same?
a. Amount of Br2
b. Concentration of H2
c. The ratio [HBr]/[H2][Br2]
d. The ratio [HBr]/[Br2]
e. The ratio [HBr]^2/[H2][Br2]
f. The total pressure in the container
Please explain each of your answers.
Thanks so much in advance!
To determine which variables will be different and which will be the same in the two containers at equilibrium, let's analyze each option:
a. Amount of Br2:
The amount of Br2 will be different in the two containers at equilibrium. In the first container, there is a 0.10 mol sample of Br2 initially. Some of this Br2 will react with H2 to form HBr, reducing the amount of Br2. However, in the second container, no Br2 is present initially, so the amount of Br2 will be zero until the equilibrium is reached.
b. Concentration of H2:
The concentration of H2 will be the same in both containers at equilibrium. The number of moles of H2 initially is the same in both containers (0.10 mol). As the reaction progresses in both containers, the amount of H2 consumed and the amount of HBr formed will both be equal, so the concentration of H2 will remain the same.
c. The ratio [HBr]/[H2][Br2]:
The ratio [HBr]/[H2][Br2] will be the same in both containers at equilibrium. This is because at equilibrium, the ratio of the concentrations of the reactants and products is constant, regardless of the initial amounts. The balanced equation indicates that for every one H2 molecule and one Br2 molecule reacting, two HBr molecules are formed.
d. The ratio [HBr]/[Br2]:
The ratio [HBr]/[Br2] will be different in the two containers at equilibrium. In the first container, where there is an initial amount of Br2 and H2, the ratio will depend on the extent of the reaction and the equilibrium concentrations. However, in the second container, where no Br2 is present initially, the ratio will be zero until the equilibrium is reached.
e. The ratio [HBr]^2/[H2][Br2]:
The ratio [HBr]^2/[H2][Br2] will be the same in both containers at equilibrium. This is because the stoichiometric coefficients in the balanced equation indicate that the ratio of the concentrations of HBr squared to the product of the concentrations of H2 and Br2 will remain constant at equilibrium.
f. The total pressure in the container:
The total pressure in both containers at equilibrium will be the same. According to Dalton's law of partial pressures, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of each individual gas. At equilibrium, the partial pressures of H2, Br2, and HBr will contribute to the total pressure, but the sum of these partial pressures will be the same in both containers.
In summary, the following will be different:
- Amount of Br2
- The ratio [HBr]/[Br2]
The following will be the same:
- Concentration of H2
- The ratio [HBr]/[H2][Br2]
- The ratio [HBr]^2/[H2][Br2]
- The total pressure in the container.