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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. (b) Nitrogen reacts with hydrogen to form ammonia. N₂(g) ... show full transcript
Worked Solution & Example Answer:4. (a) Propene is a gaseous hydrocarbon - Edexcel - GCSE Chemistry - Question 4 - 2015 - Paper 1
Step 1
Draw the structure of a molecule of propene, showing all bonds.
Answer
The structure of propene consists of three carbon atoms connected by single bonds, with one double bond between the first and second carbon atoms. Each carbon atom is bonded to hydrogen atoms to fulfill the four-bond rule of carbon. The fully drawn structure is:
H H
\ /
C=C
/ \
H H
Step 2
Calculate the minimum volume of nitrogen, in dm³, required to react completely with 1000 dm³ of hydrogen.
Answer
From the balanced equation: N₂ + 3H₂ ⇌ 2NH₃, we see that 1 volume of nitrogen reacts with 3 volumes of hydrogen. Thus, to calculate the required nitrogen volume:
Let the volume of nitrogen required be ( x ) dm³.
We have:
[ x : 1000 = 1 : 3 ]
Solving for ( x ):
[ x = \frac{1000}{3} \approx 333.33 \text{ dm³} ]
Therefore, the correct answer is option A 333 dm³.
Step 3
Explain which gas or gases will be present when equilibrium is reached.
Answer
At equilibrium, the reactants N₂ and H₂ will still be present along with the product NH₃. Since the reaction can go in both directions, some amounts of nitrogen and hydrogen will remain in the system to maintain this dynamic balance, along with the ammonia formed.
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 generally favors the side of the reaction with fewer moles of gas. In this case, there are 4 moles of gas on the reactant side (1 N₂ + 3 H₂) and only 2 moles on the product side (2 NH₃). Thus, increasing the pressure will shift the equilibrium position to the right, increasing 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
At a higher pressure, gas molecules are more concentrated, which leads to an increased rate of collisions between reactant molecules. This increased collision rate results in a faster attainment of equilibrium, as more reacting particles are available in a confined space.