Question 1: What is the general chemical formula for an ester?

Answer: R–COO–R' (where R and R' are hydrocarbon groups)

Question 2: Describe the main chemical reaction used to produce esters in the laboratory.

Answer: A reaction between a carboxylic acid and an alcohol, called esterification, usually with an acid catalyst like sulfuric acid.

Question 3: Explain why esters often have a pleasant smell and are used in perfumes.

Answer: Because many esters have volatile molecules with fruity or floral odors, making them suitable for perfumes.

Question 1: Calculate the molar mass of ethyl acetate (C4H8O2). Show your working.

Answer: Molar mass = (4×12.01) + (8×1.008) + (2×16.00) = 88.11 g/mol

Question 2: If 10 grams of acetic acid reacts completely with excess ethanol, what is the theoretical yield of ethyl acetate in grams? (Molar mass of acetic acid = 60.05 g/mol, ethanol = 46.07 g/mol, ethyl acetate = 88.11 g/mol).

Answer: Moles of acetic acid = 10 / 60.05 ≈ 0.1665 mol; Ethyl acetate yield = 0.1665 mol × 88.11 g/mol ≈ 14.68 g

Question 1: List two variables that can affect the yield of ester produced in a laboratory reaction.

Answer: Reaction temperature and amount of catalyst used.

Question 2: What safety precautions should be taken when handling sulfuric acid during esterification?

Answer: Wear gloves and eye protection, work in a well-ventilated area, and handle acids carefully to avoid spills and burns.

Question 1: A laboratory experiment produced 12 grams of a certain ester using 0.15 mol of reactants. The theoretical maximum yield based on the limiting reactant was calculated as 14 grams. Calculate the percentage yield of the ester.

Answer: Percentage yield = (Actual yield / Theoretical yield) × 100 = (12 / 14) × 100 ≈ 85.7%

Question 2: Interpret what a yield of approximately 86% indicates about the ester synthesis process.

Answer: It indicates the reaction was quite efficient, with minimal loss of product, though some side reactions or incomplete reactions may have occurred.

Question 1: Describe the role of sulfuric acid in the esterification process.

Answer: Sulfuric acid acts as a catalyst to speed up the reaction between the carboxylic acid and alcohol, and it also helps remove water formed during the reaction, shifting the equilibrium toward ester formation.

Question 2: Explain how the properties of esters make them suitable for use in perfumes and flavorings.

Answer: Esters have distinctive fruity or floral odors due to their volatile molecules, making them ideal for perfumes and flavorings. Their pleasant smell and ability to dissolve in oils and alcohols enhance their effectiveness in these applications.

Question 1: Name two common products that contain esters and describe their uses.

Answer: Fruits (natural esters give flavor and aroma), and synthetic perfumes (used to create pleasant scents).

Question 2: Discuss one way esters are used in industry beyond perfumes and flavors.

Answer: Esters are used as solvents in paints and varnishes due to their ability to dissolve many substances and evaporate easily.