SL Paper 2
Consider the following equilibrium:
\[\begin{array}{*{20}{l}} {{\text{4N}}{{\text{H}}_3}{\text{(g)}} + {\text{5}}{{\text{O}}_2}{\text{(g)}} \rightleftharpoons {\text{4NO(g)}} + {\text{6}}{{\text{H}}_2}{\text{O(g)}}}&{\Delta {H^\Theta } = - 909{\text{ kJ}}} \end{array}\]
Nitrogen reacts with hydrogen to form ammonia in the Haber process, according to the following equilibrium.
\[\begin{array}{*{20}{l}} {{{\text{N}}_{\text{2}}}{\text{(g)}} + {\text{3}}{{\text{H}}_{\text{2}}}{\text{(g)}} \rightleftharpoons {\text{2N}}{{\text{H}}_{\text{3}}}{\text{(g)}}}&{\Delta {H^\Theta } = - 92.6{\text{ kJ}}} \end{array}\]
Deduce the equilibrium constant expression, \({K_{\text{c}}}\), for the reaction.
Predict the direction in which the equilibrium will shift when the following changes occur.
The volume increases.
The temperature decreases.
\({{\text{H}}_{\text{2}}}{\text{O(g)}}\) is removed from the system.
A catalyst is added to the reaction mixture.
Define the term activation energy, \({E_{\text{a}}}\).
Nitrogen monoxide, NO, is involved in the decomposition of ozone according to the following mechanism.
\[\begin{array}{*{20}{l}} {}&{{{\text{O}}_{\text{3}}} \to {{\text{O}}_{\text{2}}} + {\text{O}} \bullet } \\ {}&{{{\text{O}}_3} + {\text{NO}} \to {\text{N}}{{\text{O}}_2} + {{\text{O}}_2}} \\ {}&{{\text{N}}{{\text{O}}_2} + {\text{O}} \bullet \to {\text{NO}} + {{\text{O}}_2}} \\ {{\text{Overall:}}}&{{\text{2}}{{\text{O}}_3} \to {\text{3}}{{\text{O}}_2}} \end{array}\]
State and explain whether or not NO is acting as a catalyst.
Define the term endothermic reaction.
Sketch the Maxwell-Boltzmann energy distribution curve for a reaction with and without a catalyst, and label both axes.
Define the term rate of reaction.
Iron, used as the catalyst in the Haber process, has a specific heat capacity of \({\text{0.4490 J}}\,{{\text{g}}^{ - 1}}{{\text{K}}^{ - 1}}\). If 245.0 kJ of heat is supplied to 8.500 kg of iron, initially at a temperature of 15.25 °C, determine its final temperature in K.