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Ammonia can be produced from the reaction of hydrogen with nitrogen - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2023 - Paper 2
Question 5
Ammonia can be produced from the reaction of hydrogen with nitrogen. (a) What is the percentage by mass of nitrogen in ammonia, NH₃? (relative atomic masses: H = 1.0... show full transcript
Worked Solution & Example Answer:Ammonia can be produced from the reaction of hydrogen with nitrogen - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2023 - Paper 2
Step 1
What is the percentage by mass of nitrogen in ammonia, NH₃?
Answer
To calculate the percentage by mass of nitrogen in ammonia (NH₃), we first need to determine the molar mass of NH₃:
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The molar mass of nitrogen (N) is 14 g/mol.
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The molar mass of hydrogen (H) is 1 g/mol, and since there are three hydrogen atoms in NH₃, the total mass from hydrogen is:
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Adding these together gives the total molar mass of NH₃:
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To find the percentage by mass of nitrogen, we use the formula:
ext{Percentage by mass of N} = rac{ ext{Mass of N}}{ ext{Total mass of NH₃}} imes 100
Substituting in the values:
ext{Percentage by mass of N} = rac{14 ext{ g/mol}}{17 ext{ g/mol}} imes 100 \\ ext{Percentage by mass of N} \\ = 82.35\%
Therefore, the closest answer is D 82%.
Step 2
Which arrow represents the activation energy for the reaction?
Answer
In Figure 8, the activation energy is represented by the energy required to reach the transition state, which is the peak of the energy profile. This is indicated by arrow Q because it shows the energy difference between the reactants and the transition state. Thus, the answer is:
Answer: B arrow Q