Question

In a chemical reaction, sum of formula weight of all reactants is 274 u and atom economy is 50%, calculate formula weight of desired product?

• A. 137 u
• B. 274 u
• C. 167 u
• D. 254 u

Hint:

Atom economy = useful product fraction; 50% means half of reactant mass forms product.

Answer 1

The Correct Option is A

Concept:
Atom economy measures the efficiency of a reaction in converting reactants into desired product: \[ \text{Atom economy} = \frac{\text{Molar mass of desired product}}{\text{Total molar mass of reactants}} \times 100 \] Step 1: Substitute given values. \[ 50 = \frac{M}{274} \times 100 \]
Step 2: Rearrange the equation. \[ \frac{50}{100} = \frac{M}{274} \] \[ 0.5 = \frac{M}{274} \]
Step 3: Calculate molar mass of product. \[ M = 0.5 \times 274 = 137 \]
Step 4: Conclusion. \[ \text{Molar mass of desired product} = 137 \text{ u} \]