Question 1: What is a limiting reactant in a chemical reaction?

Answer: A limiting reactant is the substance that is completely consumed first in a chemical reaction, limiting the amount of product formed.

Question 2: Explain why it is important to identify the limiting reactant in a chemical process.

Answer: Identifying the limiting reactant helps determine the maximum amount of product that can be formed and ensures efficient use of reactants.

Question 1: Given 10 grams of hydrogen gas (H2) and 80 grams of oxygen gas (O2), calculate the limiting reactant when they react to form water. (Molar mass: H2 = 2 g/mol, O2 = 32 g/mol, H2O = 18 g/mol).

Answer: Hydrogen is the limiting reactant because it produces less water (about 5 moles) compared to oxygen (about 2.22 moles).

Question 2: A reaction requires 50 grams of reactant A and 70 grams of reactant B. If 50 grams of A produces 80 grams of product, how much product can be formed if B is the limiting reactant, given it produces 1 gram of product per gram of B? (Assume B is limiting).

Answer: If B is limiting and produces 1 g of product per g, then 70 g of B will produce 70 g of product.

Question 1: Describe a simple experiment to identify the limiting reactant between hydrochloric acid and sodium hydroxide in a neutralization reaction. Include safety precautions.

Answer: Mix known volumes of acid and base in different ratios, observe which mixture neutralizes completely first, and ensure safety by wearing goggles and gloves. Use measured quantities for accuracy.

Question 2: A student reacts 25 grams of aluminum with excess sulfuric acid to produce aluminum sulfate. The reaction is: 2Al + 3H2SO4 → Al2(SO4)3 + 3H2. Given molar masses (Al=27 g/mol, H2SO4=98 g/mol, Al2(SO4)3=342 g/mol), identify the limiting reactant.

Answer: Aluminum is the limiting reactant because 25 g corresponds to about 0.926 mol, which limits the amount of aluminum sulfate produced.

Question 1: In industrial manufacturing of ammonia via the Haber process, nitrogen and hydrogen gases are reacted. If the reaction mixture contains 50 mol of nitrogen and 150 mol of hydrogen, which is the limiting reactant, and how does it affect the yield?

Answer: Nitrogen is the limiting reactant because the 3:1 molar ratio requires 50 mol N and 150 mol H, which is perfect for complete reaction; thus, neither is limiting in this case, but excess H2 remains.

Question 2: Explain how understanding limiting reactants can improve efficiency and reduce waste in a food manufacturing process such as baking bread.

Answer: By calculating exact amounts of ingredients needed for desired yields, manufacturers avoid excess ingredients, reduce waste, save costs, and ensure consistent product quality.