Practice Exam 2
VCE Chemistry | Chemical Reactions, Equations, Stoichiometry & The Mole
✎ Complete ALL questions on paper before opening the Model Answers lesson. No notes. Aim for 1 minute per mark.
SHORT ANSWER
Question 1 (4 marks)
Calculate the mass of CaCO₃ (M=100) needed to produce 2.24 L of CO₂ at STP.
CaCO₃ → CaO + CO₂
✎ Write your answer on paper
Question 2 (4 marks)
A 0.250 g sample of an unknown acid (monoprotic) requires 18.6 mL of 0.115 mol/L NaOH to neutralise. Calculate the molar mass of the acid.
✎ Write your answer on paper
Question 3 (4 marks)
Balance the following redox equation in acidic solution:
MnO₄⁻ + Fe²⁺ → Mn²⁺ + Fe³⁺
✎ Write your answer on paper
Question 4 (4 marks)
A compound contains 52.2% C, 13.0% H, and 34.8% O. Its molar mass is 46 g/mol. Find the molecular formula.
✎ Write your answer on paper
Question 5 (4 marks)
Explain the difference between a precipitation reaction and a neutralisation reaction. Give one example of each.
✎ Write your answer on paper
Question 6 (4 marks)
In an experiment, 3.00 g of Fe (M=56) reacts with excess HCl. Fe + 2HCl → FeCl₂ + H₂. Calculate the volume of H₂ produced at STP.
✎ Write your answer on paper
Question 7 (4 marks)
A student reacts 5.0 g of Mg (M=24) with 100 mL of 1.5 mol/L HCl. Mg + 2HCl → MgCl₂ + H₂.
Identify the limiting reagent and calculate the mass of MgCl₂ (M=95) produced.
✎ Write your answer on paper
Question 8 (4 marks)
Describe how you would prepare 250 mL of a 0.200 mol/L NaCl solution from solid NaCl (M=58.5).
✎ Write your answer on paper
EXTENDED RESPONSE
Extended Response 1: Stoichiometry
Question 9 (3 marks)
Extended Response 1: Stoichiometry (a)
When 8.10 g of Al reacts with 14.2 g of Cl₂ according to 2Al + 3Cl₂ → 2AlCl₃ (M(Al)=27, M(Cl₂)=71, M(AlCl₃)=133.5):
(i) Identify the limiting reagent.
✎ Write your answer on paper
Extended Response 1: Stoichiometry
Question 10 (2 marks)
Extended Response 1: Stoichiometry (b)
Calculate the theoretical yield of AlCl₃.
✎ Write your answer on paper
Extended Response 1: Stoichiometry
Question 11 (2 marks)
Extended Response 1: Stoichiometry (c)
If 15.0 g of AlCl₃ is actually obtained, calculate the percentage yield.
✎ Write your answer on paper
Extended Response 1: Stoichiometry
Question 12 (1 marks)
Extended Response 1: Stoichiometry (d)
Identify one reason the actual yield may be less than theoretical.
✎ Write your answer on paper
Extended Response 2: Volumetric Analysis
Question 13 (4 marks)
Extended Response 2: Volumetric Analysis (a)
A student performs a titration to determine the concentration of acetic acid (CH₃COOH) in vinegar. She uses 0.100 mol/L NaOH as the standard solution.
In her best titration, 23.45 mL of NaOH neutralised 10.00 mL of vinegar.
Write the equation and calculate the concentration of acetic acid.
✎ Write your answer on paper
Extended Response 2: Volumetric Analysis
Question 14 (2 marks)
Extended Response 2: Volumetric Analysis (b)
Calculate the mass of acetic acid (M=60) in 100 mL of the vinegar.
✎ Write your answer on paper
Extended Response 2: Volumetric Analysis
Question 15 (2 marks)
Extended Response 2: Volumetric Analysis (c)
Explain why it is important to use a primary standard to prepare the NaOH solution, or to standardise it against a primary standard before use.
✎ Write your answer on paper
✓ Finished? Open the next lesson – Model Answers – to mark your work.
