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The graph shows the percentage yield of ammonia produced from nitrogen and hydrogen at different temperatures and pressures - HSC - SSCE Chemistry - Question 30 - 2015 - Paper 1
Question 30
The graph shows the percentage yield of ammonia produced from nitrogen and hydrogen at different temperatures and pressures. The Haber process is the main industria... show full transcript
Worked Solution & Example Answer:The graph shows the percentage yield of ammonia produced from nitrogen and hydrogen at different temperatures and pressures - HSC - SSCE Chemistry - Question 30 - 2015 - Paper 1
Step 1
Explain the conditions used in the Haber process concerning yield and rate considerations.
Answer
In the Haber process, the reaction between nitrogen and hydrogen produces ammonia in an exothermic process. According to Le Chatelier's principle, the yield can be maximized by manipulating temperature and pressure.
From the graph, we see that as pressure increases, the yield of ammonia also increases. This is because higher pressure favors the formation of fewer moles of gas, moving the equilibrium to the right. Therefore, in the Haber process, a high pressure of around 300 atm is commonly utilized to achieve a higher yield.
Regarding temperature, the yield increases at lower temperatures. However, the reaction rate decreases, making it impractical to perform the reaction at very low temperatures. Therefore, a compromise temperature of around 450°C is typically used. This balances a reasonable yield with an acceptable reaction rate.
Step 2
Relate the information in the graph to these conditions.
Answer
The graph illustrates the relationship between temperature and pressure on the yield of ammonia. As temperature rises, the yield of ammonia decreases for all pressure levels shown. This indicates that maintaining a lower temperature is advantageous for achieving a higher yield, which aligns with the exothermic nature of the reaction. High pressures consistently lead to improved yields, reinforcing the need to operate under such conditions to optimize the production of ammonia in the Haber process.
Step 3
Link the graph to temperature and pressure.
Answer
The graph explicitly shows how both temperature and pressure affect ammonia yield. At lower temperatures, regardless of the pressure applied, the yield is notably higher. Conversely, as temperature increases towards 600°C, even at higher pressures, the yield significantly declines. This highlights the critical role of both parameters in achieving the desired yield in the Haber process.