Which statement best defines atom economy?

Which statement best defines atom economy?

• A. The energy efficiency of a process.
• B. Atom economy = (mass of desired product / total mass of reactants) x 100.
• C. The rate at which reactants are consumed.
• D. The percentage yield of the reaction.

Answer: (D)

Atom economy is about how much of the reactants’ mass ends up in the desired product, so a high atom economy means less waste and a more efficient process. The best way to express this is with the formula for atom economy: atom economy = (mass of the desired product / total mass of reactants) × 100. In more precise terms for a balanced equation, it’s often written using molar masses: atom economy = (molar mass of the desired product) ÷ (sum of molar masses of all reactants) × 100. This directly links the amount of material that actually becomes the product to the total material you started with. The other ideas describe different things. Energy efficiency looks at how much energy is used or wasted, not how much of the reactants’ mass goes into the product. The rate at which reactants are consumed is about how fast the reaction happens, not how much mass ends up in the target product. The percentage yield tells you how much product you obtained compared with the theoretical maximum, which is about yield, not the proportion of reactant mass converted into the desired product.

Atom economy is about how much of the reactants’ mass ends up in the desired product, so a high atom economy means less waste and a more efficient process.

The best way to express this is with the formula for atom economy: atom economy = (mass of the desired product / total mass of reactants) × 100. In more precise terms for a balanced equation, it’s often written using molar masses: atom economy = (molar mass of the desired product) ÷ (sum of molar masses of all reactants) × 100. This directly links the amount of material that actually becomes the product to the total material you started with.

The other ideas describe different things. Energy efficiency looks at how much energy is used or wasted, not how much of the reactants’ mass goes into the product. The rate at which reactants are consumed is about how fast the reaction happens, not how much mass ends up in the target product. The percentage yield tells you how much product you obtained compared with the theoretical maximum, which is about yield, not the proportion of reactant mass converted into the desired product.