A table lists some bond energies. Use these values to calculate the enthalpy change, $\Delta H$, for the thermal decomposition of hydrogen bromide, HBr, using the equation shown.
At $700\,\text{K}$, roughly $10\%$ of an HBr sample is decomposed. Changing the temperature affects both how fast HBr decomposes and the proportion that decomposes. The Boltzmann distribution for HBr at $700\,\text{K}$ is shown. $E_a$ is the activation energy for the reaction.
On the same axes, sketch a second curve to show the Boltzmann distribution at a higher temperature.
With reference to the curves, state and explain the effect of increasing temperature on the rate of decomposition of HBr.
The decomposition of HBr is endothermic. State the effect of increasing temperature on the percentage of HBr that decomposes. Use Le Chatelier’s principle to explain your answer.
At $700\,\text{K}$ HBr is approximately $10\%$ decomposed but hydrogen iodide, HI, is approximately $20\%$ decomposed. Explain this difference with reference to bond strengths and the factors that affect them.
At temperatures above $1500\,\text{K}$, HCl decomposes. A $0.300\,\text{mol}$ sample of HCl was allowed to decompose in a sealed container. The equilibrium mixture obtained was found to contain $1.50 \times 10^{-2}\,\text{mol}$ of $\text{Cl}_2$. Calculate the amounts, in $\text{mol}$, of $\text{H}_2$ and HCl in the equilibrium mixture.
Calculate each gas’s mole fraction in the equilibrium mixture.
In a separate experiment carried out under different conditions, an equilibrium mixture was formed and the mole fractions for each species are shown. Write the expression for the equilibrium constant, $K_p$, for the decomposition of HCl: $\text{2HCl}(g) \rightleftharpoons \text{H}_2(g) + \text{Cl}_2(g)$.
Explain why knowing the system’s total pressure is not necessary in order to calculate $K_p$ for this experiment.
Calculate $K_p$ for this experiment.
Explain why it is unnecessary to know the total pressure of the system in order to calculate $K_p$ for this experiment.
Calculate the equilibrium constant, $K_p$, for this experiment.