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4. (a) Propene is a gaseous hydrocarbon - Edexcel - GCSE Chemistry - Question 4 - 2015 - Paper 1
Question 4
4. (a) Propene is a gaseous hydrocarbon. Draw the structure of a molecule of propene, showing all bonds. (2) (b) Nitrogen reacts with hydrogen to form ammonia. N₂... show full transcript
Worked Solution & Example Answer:4. (a) Propene is a gaseous hydrocarbon - Edexcel - GCSE Chemistry - Question 4 - 2015 - Paper 1
Step 1
Step 2
Calculate the minimum volume of nitrogen, in dm³, required to react completely with 1000 dm³ of hydrogen.
Answer
According to the reaction, 1 volume of nitrogen reacts with 3 volumes of hydrogen:
To find the volume of nitrogen needed for 1000 dm³ of hydrogen, we can set up a ratio:
If 3 volumes of H₂ require 1 volume of N₂, then 1000 dm³ of H₂ will require:
Thus, the correct answer is A 333 dm³.
Step 3
Explain which gas or gases will be present when equilibrium is reached.
Answer
At equilibrium, the gases present will be nitrogen (N₂), hydrogen (H₂), and ammonia (NH₃). Since the formation of ammonia is not a complete reaction, some of the reactants (N₂ and H₂) will remain alongside the product (NH₃). The dynamic balance of reactants and products will stabilize at equilibrium.
Step 4
Explain the effect on the equilibrium yield of ammonia, if the process is carried out at a pressure higher than 200 atm.
Answer
Increasing the pressure shifts the equilibrium position to the side with fewer gas molecules according to Le Chatelier's principle. Since the formation of ammonia from nitrogen and hydrogen results in a decrease in the number of moles of gas (from 4 moles to 2 moles), a higher pressure will increase the yield of ammonia.
Step 5
Explain the effect on the rate of attainment of equilibrium, if the process is carried out at a pressure higher than 200 atm.
Answer
Higher pressure increases the concentration of the gaseous reactants, which leads to more frequent collisions between reactant molecules. Consequently, the rate of reaction will increase, allowing the system to reach equilibrium more quickly.