One of the steps in the Ostwald process for the production of nitric acid involves oxidation of ammonia.
4NH3 (aq) + 5O2 (g) <---> 4NO (g) + 6H2O (g), Delta H= -905kJ
a) State the reaction conditions that favour the production of nitrogen monoxide.
b) A rhodium/platinum alloy is used as a catalyst. What effect does the catalyst have on the position of the equilibrium. Explain.
c) A relatively low pressure of about 710 kPa is used. Suggest why.
d) In the next step of the Ostwald process, nitrogen monoxide is mixed with air to form nitrogen dioxide:
2NO (g) + O2(g) <----> 2NO2(g) , Delta H= -115kJ
Why are the gases cooled for this reaction?
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a) State the reaction conditions that favour the production of nitrogen monoxide.
If this question is asking for the best production AT EQUILIBRIUM then cool and low pressure. Under these conditions; however, the reaction is too slow to be useful and generally, in real practice, higher T and higher P are used.
b) A rhodium/platinum alloy is used as a catalyst. What effect does the catalyst have on the position of the equilibrium. Explain.
A catalyst changes ONLY the rate of the reaction. It has no effect on the final equilibrium.
c) A relatively low pressure of about 710 kPa is used. Suggest why.
Low pressure shifts the reaction to the side with fewer moles. That is the product side
d) In the next step of the Ostwald process, nitrogen monoxide is mixed with air to form nitrogen dioxide:
2NO (g) + O2(g) <----> 2NO2(g) , Delta H= -115kJ
Why are the gases cooled for this reaction?
<b.Cooling uses up the heat produced and shifts the reaction to the right.
a) The reaction conditions that favor the production of nitrogen monoxide include a high concentration of ammonia (NH3), a high partial pressure of oxygen (O2), and a low temperature. These conditions shift the equilibrium towards the formation of nitrogen monoxide.
b) The catalyst (rhodium/platinum alloy) used in the Ostwald process for the production of nitric acid does not affect the position of the equilibrium. It speeds up the reaction by providing an alternative reaction pathway with lower activation energy. This enables the reaction to reach equilibrium faster, but it does not alter the equilibrium constant or the position of the equilibrium.
c) A relatively low pressure of about 710 kPa (kilopascal) is used in the Ostwald process to favor the production of nitrogen monoxide. At lower pressures, according to Le Chatelier's principle, the equilibrium will shift towards the side with the smaller number of gas molecules. In this case, the production of nitrogen monoxide (NO) involves fewer gas molecules compared to the reactants (ammonia and oxygen), so reducing the pressure favors the formation of nitrogen monoxide.
d) The gases are cooled for the reaction of nitrogen monoxide (NO) with oxygen (O2) to form nitrogen dioxide (NO2) because the reaction is exothermic (ΔH = -115 kJ). Cooling the gases helps to maintain a lower temperature, which favors the production of nitrogen dioxide according to Le Chatelier's principle. Lower temperatures shift the equilibrium towards the formation of more products, in this case, nitrogen dioxide.
a) The reaction conditions that favor the production of nitrogen monoxide (NO) can be achieved by increasing the temperature and decreasing the pressure. This reaction is exothermic, meaning it releases heat. Therefore, increasing the temperature will shift the equilibrium towards the products (NO and H2O), favoring the production of NO. Lowering the pressure also helps to shift the equilibrium towards the side with fewer moles of gas, which in this case is NO.
b) The rhodium/platinum alloy catalyst used in the Ostwald process has no effect on the position of the equilibrium. A catalyst speeds up the rate of the reaction by providing an alternative pathway with a lower activation energy. It does not affect the stoichiometry or position of the equilibrium. Thus, the catalyst does not influence the amount of NO produced, but it helps to increase the rate of the reaction.
c) The relatively low pressure of about 710 kPa is used in the Ostwald process for several reasons. Firstly, a lower pressure helps to shift the equilibrium towards the products, since the reaction involves a decrease in the total moles of gas. As a result, more NO is produced. Secondly, a lower pressure is more practical and economical for industrial production, as it reduces the energy required to pressurize the reaction vessel.
d) The gases are cooled for the reaction between nitrogen monoxide (NO) and oxygen (O2) to form nitrogen dioxide (NO2) because the reaction is exothermic. Cooling the gases helps to remove the excess heat produced during the reaction, preventing an increase in temperature which could favor the reverse reaction. By maintaining a lower temperature, the yield of nitrogen dioxide can be increased, resulting in a higher overall production of nitric acid.