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The atom economy (AE) of a reaction is a measure of the mass of atoms in the starting materials that are incorporated into the desired product - HSC - SSCE Chemistry - Question 31 - 2024 - Paper 1
Question 31
The atom economy (AE) of a reaction is a measure of the mass of atoms in the starting materials that are incorporated into the desired product. Higher AE means lower... show full transcript
Worked Solution & Example Answer:The atom economy (AE) of a reaction is a measure of the mass of atoms in the starting materials that are incorporated into the desired product - HSC - SSCE Chemistry - Question 31 - 2024 - Paper 1
Step 1
Which of these two processes is preferable for urea production?
Answer
The process using dimethyl carbonate (DMC) is preferable for urea production compared to the reaction with phosgene. The atom economy for the DMC process is 48.4%, while that for the phosgene reaction is only 35.9%. This indicates that more of the starting materials are converted into the desired product (urea) in the DMC process, resulting in less waste.
Additionally, the use of DMC is advantageous due to its low toxicity in comparison to phosgene, which is a highly toxic substance. The reaction with DMC also requires less ammonia (2 moles compared to 4 moles for phosgene), further minimizing the amount of harmful reactants used.
In conclusion, the production of urea via DMC is more efficient and safer due to its higher atom economy and lower toxicity.