Separate chemistry 1 Study Guide

In chemistry, the theoretical yield of a reaction is the maximum amount of product that could possibly be formed from a given amount of reactants, assuming perfect conditions and 100% efficiency. This is often calculated based on stoichiometry. However, in practical laboratory settings, the actual yield—the amount of product actually obtained—is almost always less than the theoretical yield. There are several reasons for this discrepancy. Firstly, reactions may be incomplete; not all reactant molecules might convert to product molecules. Secondly, practical losses can occur during experimentation, such as product remaining in glassware, transferred incompletely, or lost during purification steps like filtration or distillation. Thirdly, unwanted side reactions can take place, consuming some of the reactants to form different products that are not the desired outcome, thereby reducing the amount of the desired product.

Atom economy is a measure of how efficiently reactant atoms are incorporated into the desired product during a chemical reaction. It's a key concept in green chemistry, aiming to minimise waste by maximising the conversion of starting materials into useful products. A high atom economy indicates that most atoms from the reactants end up in the desired product, rather than in unwanted by-products. This means less waste is produced, which is better for the environment and can also reduce purification costs. The formula for calculating atom economy is the (relative formula mass of desired product / relative formula mass of all reactants) × 100%.