Category 1: Relative Masses and the Mole Concept (5 Questions)
Relative Formula Mass (Mr): Calculate the Mr for:
(a) Ammonium Sulfate, (NH4)2SO4
(b) Hydrated Copper(II) Sulfate, CuSO4.5H2O
Mass to Moles: How many moles are present in 10g of Calcium Carbonate (CaCO3)?
Moles to Mass: Calculate the mass of 0.05 moles of Sodium Carbonate (Na2CO3).
Avogadro’s Constant: How many atoms are present in 2.3g of Sodium metal? (Na)
Percentage Composition: Calculate the percentage by mass of Nitrogen in Urea, CO(NH2)2.
Category 2: Empirical and Molecular Formulae (5 Questions)
Empirical Formula (EF): A compound contains 40% Carbon, 6.7% Hydrogen, and 53.3% Oxygen by mass. Determine its EF.
Molecular Formula (MF): A compound has the EF CH2 and a relative formula mass of 84. Find its MF.
Water of Crystallisation: 5.00g of hydrated Barium Chloride (BaCl@.xH2O) was heated until all water was lost. The remaining anhydrous salt weighed 4.26g. Find the value of x.
Reduction of Oxides: 1.6g of an oxide of Iron was reduced by Hydrogen to form 1.12g of Iron metal. Determine the formula of the oxide.
Combustion Analysis: When 0.1 moles of a hydrocarbon CxHy is burned completely, it produces 0.3 moles of CO2 and 0.4 moles of H2O. Find the formula of the hydrocarbon.
Category 3: Molar Volume of Gases (5 Questions)
(Assume Molar Volume = 22.4 dm3 at s.t.p.)
11. Volume to Moles: Calculate the number of moles in 480 cm3 of Oxygen gas at s.t.p.
12. Mass to Volume: What volume (at s.t.p.) is occupied by 4.4g of Carbon Dioxide?
13. Reacting Volumes (Gay-Lussac): For the reaction N2 + 3H2 ⇌ 2NH3, what volume of Ammonia is produced from 15 cm3 of Nitrogen?
14. Density: Calculate the density of Chlorine gas (Cl2) in g/dm3 at s.t.p.
15. Unknown Gas: 0.28g of a gas occupies 240 cm3 at s.t.p. Calculate its Mr and identify the gas.
Category 4: Reacting Masses & Stoichiometry (5 Questions)
Basic Mass-Mass: What mass of Magnesium Oxide is formed when 12g of Magnesium burns in excess Oxygen?
- 2Mg + O2 → 2MgO
Thermal Decomposition: What mass of CO2 is released when 20g of Calcium Carbonate is heated?
- CaCO3 → CaO CO2
Limiting Reagent: If 5g of Iron reacts with 5g of Sulfur, which is the limiting reagent?
- Fe + S → FeS
Percentage Yield: A student expected 10g of product but only obtained 8g. Calculate the percentage yield.
Purity: 5.0g of impure Zinc reacted with excess HCl to produce 1.2 dm3 of H2 at r.t.p. Calculate the percentage purity of the Zinc.
Category 5: Solutions and Concentrations (5 Questions)
Molarity (mol/dm3): Calculate the concentration of a solution containing 4g of NaOH dissolved in 250 cm3 of water.
Mass in Solution: How many grams of Silver Nitrate (AgNO3) are needed to prepare 500 mL of a 0.1 mol dm-3 solution?
Dilution: If 100 cm3 of 2.0 mol dm-3 HCl is diluted to 500 cm3, what is the new concentration?
Gram Concentration: Convert 0.25 mol dm-3 of H2SO4 into g dm-3.
Ion Concentration: What is the concentration of Cl- ions in a 0.5 mol dm-3 solution of MgCl2?
Category 6: Titration Calculations (5 Questions)
Acid-Base Titration: 25 cm3 of 0.1 mol dm-3 required 20.0 cm3 of H2SO4 for neutralization. Calculate the molarity of the acid.
- 2NaOH + H2SO4 → Na2SO4 + 2H2O
Back Titration (Advanced): An excess of 50 cm3 of 1.0 mol dm-3 HCl was added to 2g of impure CaCO3. The excess acid required 10cm3 of 1.0 mol dm-3 NaOH for neutralization. Calculate the % purity of the carbonate.
Unknown Metal: A divalent metal M reacts with HCl. 0.12g of M produced 120 cm3 of H2 at r.t.p. Find the Ar of M.
- M + 2HCl → MCl2 + H2
Gas from Solid: What volume of CO2 (at r.t.p.) is produced when 5.3g of Na2CO3 reacts with excess HCl?
- Na2CO3 + 2HCl → 2NaCl + CO2 + H2O
