Unit Quiz
Quiz Instructions
Complete all 10 questions without notes first, then check answers.
Scoring: 9-10 = Excellent | 7-8 = Good | 5-6 = Review needed | Below 5 = Retake unit
Quiz Questions
Q1: How many moles are in 88 g of CO2? (Molar mass = 44 g/mol)
Answer: 88 g / 44 g/mol = 2 moles CO2
Q2: For 2H2 + O2 -> 2H2O, how many moles of H2O form from 5 mol H2?
Answer: Ratio 2:2, so 5 mol H2 produces 5 mol H2O
Q3: What mass is 3 mol of NaCl? (Molar mass = 58.5 g/mol)
Answer: 3 mol x 58.5 g/mol = 175.5 g NaCl
Q4: For N2 + 3H2 -> 2NH3, with 2 mol N2 and 3 mol H2, which is limiting?
Answer: 2 mol N2 needs 6 mol H2 (1:3 ratio). Only have 3 mol H2. H2 is limiting.
Q5: How many molecules are in 0.25 mol of any substance?
Answer: 0.25 x 6.02 x 10^23 = 1.505 x 10^23 molecules
Q6: If theoretical yield is 80 g and actual yield is 60 g, what is percent yield?
Answer: (60/80) x 100% = 75%
Q7: What volume does 4 mol of gas occupy at STP?
Answer: 4 mol x 22.4 L/mol = 89.6 L
Q8: Calculate the molar mass of Ca(OH)2.
Answer: Ca = 40 + 2(O = 16) + 2(H = 1) = 40 + 32 + 2 = 74 g/mol
Q9: For 2Mg + O2 -> 2MgO, how many grams of MgO form from 24 g Mg?
Answer: 24 g Mg = 1 mol Mg -> 1 mol MgO = 40 g. 40 g MgO
Q10: A reaction has 70% yield. If you need 100 g of product, how much theoretical yield do you need?
Answer: 100 g / 0.70 = 142.9 g theoretical yield