Question

What is value of percent atom economy if formula weight of product is 46 u and sum of formula weight of all reactants is 92 u?

• A. 35
• B. 50
• C. 40
• D. 45

Hint:

Atom economy is simply a percentage fraction of "what you want" divided by "everything you put in". Since the product weight (46) is exactly half of the total reactant weight (92), it is an instant 50

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks us to calculate the percent atom economy of a chemical reaction given the formula weight of the desired product and the total sum of the formula weights of all the starting reactants.

Step 2: Key Formula or Approach:
Atom economy is a fundamental principle of green chemistry that measures the efficiency of a chemical process by calculating how many atoms from the reactants end up in the final desired product. The formula is written as: $$ \% \text{ Atom Economy} = \frac{\text{Formula weight of the desired product}}{\text{Sum of formula weights of all reactants}} \times 100 $$

Step 3: Detailed Explanation:
From the problem statement, we have the following metrics:

• Formula weight of the desired product = $46\ \text{u}$

• Sum of formula weights of all reactants = $92\ \text{u}$
Substitute these numerical values directly into the green chemistry metric equation: $$ \% \text{ Atom Economy} = \frac{46}{92} \times 100 $$ Notice that $46$ is exactly half of $92$ ($\frac{46}{92} = \frac{1}{2}$): $$ \% \text{ Atom Economy} = 0.5 \times 100 = 50\% $$

Step 4: Final Answer: The value of the percent atom economy is 50