Nitrobenzene (C₆H₅NO₂) is used in small quantities as a flavoring agent or in perfumes but can be toxic in large amounts. It is produced by reaction of benzene (C₆H₆) with nitric acid:
C₆H₆(l) + HNO₃(aq) → C₆H₅NO₂(l) + H₂O(l)
a. Identify the limiting reagent in the reaction of 27.5 g of nitric acid with 75 g of benzene.

Verified step by step guidance

1. Step 1: Write the balanced chemical equation for the reaction. The given equation is already balanced: C₆H₆(l) + HNO₃(aq) → C₆H₅NO₂(l) + H₂O(l). This shows a 1:1 molar ratio between benzene (C₆H₆) and nitric acid (HNO₃).
2. Step 2: Calculate the molar masses of the reactants. Use the periodic table to find the atomic masses: C₆H₆ (benzene) has a molar mass of approximately 78.11 g/mol, and HNO₃ (nitric acid) has a molar mass of approximately 63.01 g/mol.
3. Step 3: Convert the given masses of the reactants to moles. Use the formula: moles = mass / molar mass. For benzene: moles of C₆H₆ = 75 g / 78.11 g/mol. For nitric acid: moles of HNO₃ = 27.5 g / 63.01 g/mol.
4. Step 4: Compare the mole ratio of the reactants to the stoichiometric ratio from the balanced equation. Since the reaction requires a 1:1 molar ratio, determine which reactant has fewer moles. The reactant with fewer moles is the limiting reagent.
5. Step 5: Conclude which reactant is the limiting reagent based on the comparison in Step 4. The limiting reagent is the one that will be completely consumed first, determining the maximum amount of product that can be formed.

Key Concepts

Limiting Reagent

The limiting reagent in a chemical reaction is the reactant that is completely consumed first, thus determining the maximum amount of product that can be formed. To identify it, one must calculate the moles of each reactant and compare their stoichiometric ratios based on the balanced chemical equation.

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves using the coefficients from the balanced equation to relate the amounts of substances involved, allowing for the determination of how much of each reactant is needed or how much product can be produced.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting between grams and moles, which is necessary for stoichiometric calculations to determine the limiting reagent in a reaction.