Question

What is the percentage atom economy when formula weight of product is \(65\) u and the sum of formula weight of reactant is \(130\) u?

• A. \(65\%\)
• B. \(70\%\)
• C. \(40\%\)
• D. \(50\%\)

Hint:

Atom economy is the product formula weight divided by the total reactant formula weight, times 100.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Atom economy tells us what fraction of the mass of all reactants ends up in the desired product.
A higher value means less waste, which is the idea behind green chemistry.

Step 2: Key Formula:
\[ \text{Atom economy} = \frac{\text{formula weight of product}}{\text{sum of formula weights of reactants}} \times 100 \]

Step 3: Substitute the Values:
Formula weight of product = \(65\) u.
Sum of formula weights of reactants = \(130\) u.
\[ \text{Atom economy} = \frac{65}{130}\times 100 = 0.5 \times 100 = 50\% \]

Step 4: Check the Other Options:
\(65\%\) would need the ratio 0.65, which is not what 65/130 gives. \(70\%\) and \(40\%\) correspond to ratios 0.70 and 0.40, which would need product weights of 91 u and 52 u. Only the ratio 0.5 matches the data, so (D) is correct.

Final Answer:
The atom economy is 50%, which is option (D). \[ \boxed{\text{(D) } 50\%} \]