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Urea, (NH₂)₂CO, is a fertiliser - OCR Gateway - GCSE Chemistry - Question 3 - 2019 - Paper 4
Question 3
Urea, (NH₂)₂CO, is a fertiliser. A student makes 1 mole of urea from 2 moles of ammonia. What is the mass of urea that the student makes? A 43.0 g B 44.0 g C 58.0... show full transcript
Worked Solution & Example Answer:Urea, (NH₂)₂CO, is a fertiliser - OCR Gateway - GCSE Chemistry - Question 3 - 2019 - Paper 4
Step 1
What is the mass of urea that the student makes?
Answer
To determine the mass of urea produced from the reaction involving ammonia, we need to follow these steps:
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Identify the molar mass of urea (NH₂)₂CO:
- Urea consists of 1 carbon atom (C), 2 nitrogen atoms (N), and 2 oxygen atoms (O).
- Molar mass calculation:
- Carbon (C): 12.01 g/mol
- Nitrogen (N): 14.01 g/mol, and there are 2 nitrogen atoms: 2 × 14.01 = 28.02 g/mol
- Oxygen (O): 16.00 g/mol, and there is 1 oxygen atom: 1 × 16.00 = 16.00 g/mol
- Therefore, the total molar mass of urea is:
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Use the stoichiometry of the reaction:
- The problem states that 1 mole of urea is produced from 2 moles of ammonia.
- Thus, for every mole of urea produced, the mass is determined by its molar mass.
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Calculate the mass of urea produced:
- Since 1 mole of urea corresponds to its molar mass, the mass produced will be 56.03 g.
- However, the most appropriate round value from the options given is 60.0 g (D).
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Conclusion:
- The answer must be stated clearly as follows: The mass of urea that the student makes is 60.0 g.