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In a chemical reaction, the theoretical yield is the maximum amount of product that can be produced from the given amounts of reactants, assuming 100% efficiency in the reaction. To calculate the theoretical yield, you first need to identify the limiting reactant, which is the reactant that is completely consumed first, thus limiting the amount of product formed. In the given exercise, benzene is determined to be the limiting reactant. Once identified, you use its amount to calculate how much of the product, bromobenzene, can theoretically be formed. To do this, convert the mass of the limiting reactant to moles using its molar mass. Then, use the balanced chemical equation to relate the moles of reactants to the moles of products, assuming they react in a 1:1 ratio. Finally, convert the moles of the product back to grams using its molar mass, giving you the theoretical yield. This calculation is crucial in predicting the efficiency and feasibility of a reaction in a real-world setting.

The percentage yield is a measure of the efficiency of a chemical reaction, comparing the actual amount of product obtained to the theoretical yield. It's calculated using the formula: \[\text{Percentage yield} = \left(\frac{\text{Actual yield}}{\text{Theoretical yield}}\right) \times 100\%\]In the given exercise, the actual yield of bromobenzene is provided as 42.3 g, and the theoretical yield was previously calculated as 60.3 g. By substituting these values into the formula, the percentage yield is found to be 70.1%.This value reflects how close the reaction arrived at its theoretical potential. A percentage yield of less than 100% typically occurs because of various factors, such as incomplete reactions, side reactions, or loss of product during the purification process. Understanding percentage yield helps chemists optimize reactions, conserve resources, and deliver desired results more reliably.

Molar mass is a fundamental concept in chemistry that represents the mass of one mole of a chemical substance. It is typically expressed in grams per mole (g/mol). Calculating molar mass is a crucial step in converting between mass and moles, which is an essential operation in stoichiometry.To determine the molar mass of a compound, sum the atomic masses of all the atoms present in one molecule of the compound. For example, to calculate the molar mass of benzene \(\text{C}_6\text{H}_6\),add the atomic masses of six carbon atoms \((6 \times 12.01)\) and six hydrogen atoms \((6 \times 1.008)\), resulting in 78.11 g/mol. Similarly, you calculate molar masses for bromine \(\text{Br}_2\) and bromobenzene \(\text{C}_6\text{H}_5\text{Br}\).Understanding molar mass is vital for quantifying substances in a reaction and converting between different units such as grams and moles. It forms the foundation for determining quantities and yields in chemistry, making accurate calculations essential for successfully executing and evaluating chemical processes.