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Nitrogen oxides are commonly found in the atmosphere in areas where there is serious atmospheric pollution - VCE - SSCE Chemistry - Question 5 - 2011 - Paper 1
Question 5
Nitrogen oxides are commonly found in the atmosphere in areas where there is serious atmospheric pollution. Nitrogen monoxide, NO, is generated from the reaction bet... show full transcript
Worked Solution & Example Answer:Nitrogen oxides are commonly found in the atmosphere in areas where there is serious atmospheric pollution - VCE - SSCE Chemistry - Question 5 - 2011 - Paper 1
Step 1
Explain why the rate of the reaction $N_2(g) + O_2(g) \rightarrow 2NO(g)$ will never be greater than the rate of the reaction $2NO(g) \rightarrow N_2(g) + O_2(g)$ once the system is reaching equilibrium.
Answer
In a chemical equilibrium, the rates of the forward and reverse reactions become equal. As the system approaches equilibrium, the rate of the forward reaction () decreases because the concentration of the reactants diminishes. Concurrently, the rate of the reverse reaction () increases as the concentration of the products () rises. Once equilibrium is reached, both rates stabilize, ensuring that neither reaction surpasses the other in terms of rate.
Step 2
Explain why combustion engines are such good chemical environments for the production of NO(g).
Answer
Combustion engines provide high temperatures and pressures, which favor the formation of nitrogen oxides like NO(g). The high energy conditions allow sufficient kinetic energy for nitrogen and oxygen molecules to collide and react favorably. Additionally, the presence of catalysts in exhaust systems decreases the activation energy required for these reactions, enhancing the overall reaction rate and making the combustion environment particularly effective for producing NO(g).
Step 3
Sketch, on the axes provided below, a fully labelled energy profile diagram for the decomposition reaction of NO. Indicate on the diagram the effect of using a catalyst in this reaction.
Answer
The energy profile diagram for the decomposition of NO will illustrate the energy changes during the reaction. The x-axis will represent time, and the y-axis will represent enthalpy. The diagram will show a potential energy barrier for the reaction. When a catalyst is present, this barrier is lowered. Indicate the original activation energy and the reduced activation energy with the catalyst, clearly labeling both sections in the sketch.