Photo AI
8. Ammonia can be produced from the reaction of hydrogen with nitrogen - Edexcel - GCSE Chemistry - Question 8 - 2023 - Paper 2
Question 8
8. 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 ... show full transcript
Worked Solution & Example Answer:8. Ammonia can be produced from the reaction of hydrogen with nitrogen - Edexcel - GCSE Chemistry - Question 8 - 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 find the molar mass of NH₃:
- Molar mass of N = 14 g/mol
- Molar mass of H = 1 g/mol
The formula for ammonia, NH₃, consists of 1 nitrogen atom and 3 hydrogen atoms. Thus,
Next, we calculate the percentage by mass of nitrogen:
The correct answer is D. 82%.
Step 2
Which arrow represents the activation energy for the reaction?
Answer
To identify the activation energy from the energy profile diagram, we look for the energy barrier that must be overcome for the reaction to proceed. In this case, arrow R represents the activation energy as it indicates the energy required to reach the transition state from the reactants.
Step 3
Explain why the boiling points of ammonia and silicon dioxide are so different.
Answer
The difference in boiling points between ammonia (NH₃) and silicon dioxide (SiO₂) can be attributed to the types of intermolecular forces present in each substance.
-
Intermolecular Forces in NH₃: Ammonia has hydrogen bonds due to the presence of a highly electronegative nitrogen atom bonded to hydrogen atoms. While hydrogen bonding is a strong intermolecular force, it is not as significant as the covalent network bonding present in silicon dioxide.
-
Intermolecular Forces in SiO₂: In contrast, silicon dioxide has a giant covalent structure where each silicon atom is covalently bonded to four oxygen atoms. This network of strong covalent bonds results in a much higher boiling point.
-
Conclusion: Therefore, the boiling point of ammonia is much lower (-33°C) because it primarily experiences hydrogen bonding, while silicon dioxide has a very high boiling point (2230°C) due to its extensive covalent network structure.