Stoichiometry Banker

1. (a) How many moles of sodium hydroxide are in 25.0 cm³ of 0.200 mol/dm³ aqueous sodium hydroxide?A 0.00500B 0.0500C 5.00D 8.00 [1]

25.0 cm³ of aqueous sodium hydroxide is exactly neutralised by 20.00 cm³ of 0.100 mol/dm³ hydrochloric acid.NaOH + HCl → NaCl + H₂O

1. (a) Calculate the number of moles of hydrochloric acid used. [1]
2. (b) Calculate the concentration of the sodium hydroxide in mol/dm³. [2]

1. (a) What is the concentration, in g/dm³, of 0.150 mol/dm³ aqueous sodium hydroxide? [Mr: NaOH, 40]A 0.00375 g/dm³B 3.75 g/dm³C 6.00 g/dm³D 267 g/dm³ [1]

25.0 cm³ of 0.120 mol/dm³ aqueous sodium hydroxide is neutralised by 18.75 cm³ of dilute sulfuric acid.2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O

1. (a) Calculate the number of moles of sodium hydroxide in 25.0 cm³. [1]
2. (b) Calculate the concentration of the sulfuric acid in mol/dm³. [2]
3. (c) Calculate the concentration of the sulfuric acid in g/dm³. [Mr: H₂SO₄, 98] [1]

A student dilutes 25.0 cm³ of a brand of vinegar to 250 cm³ with distilled water. 25.0 cm³ of the diluted vinegar needs 21.60 cm³ of 0.100 mol/dm³ aqueous sodium hydroxide for neutralisation.CH₃COOH + NaOH → CH₃COONa + H₂O

1. (a) Calculate the concentration of ethanoic acid in the diluted vinegar. [2]
2. (b) Calculate the concentration of ethanoic acid in the original vinegar in mol/dm³ and in g/dm³. [Mr: CH₃COOH, 60] [2]

An antacid tablet of mass 0.500 g contains calcium carbonate. It is added to 50.0 cm³ of 0.500 mol/dm³ hydrochloric acid (an excess). When the reaction stops, the excess acid in the whole solution is titrated and needs 64.00 cm³ of 0.250 mol/dm³ aqueous sodium hydroxide.CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂; NaOH + HCl → NaCl + H₂O [Mr: CaCO₃, 100]

1. (a) Calculate the number of moles of hydrochloric acid added at the start. [1]
2. (b) Calculate the number of moles of hydrochloric acid left over (in excess). [1]
3. (c) Calculate the mass of calcium carbonate in the tablet. [2]
4. (d) Calculate the percentage by mass of calcium carbonate in the tablet. [1]

1.40 g of the hydroxide of a Group I metal, MOH, is dissolved in water and made up to 250 cm³ in a volumetric flask. 25.0 cm³ of this solution is neutralised by 25.00 cm³ of 0.100 mol/dm³ hydrochloric acid.MOH + HCl → MCl + H₂O [Ar: H, 1; O, 16]

1. (a) Calculate the number of moles of MOH in 25.0 cm³ of the solution and in the 250 cm³ flask. [2]
2. (b) Calculate the relative formula mass of MOH. [1]
3. (c) Deduce the relative atomic mass of M and identify M. [2]

1. (a) How many moles of carbon dioxide molecules are in 4.4 g of carbon dioxide? [Mr: CO₂, 44]A 0.010B 0.10C 1.0D 10 [1]

In a lime kiln in Sindh, limestone (calcium carbonate) is heated strongly.CaCO₃ → CaO + CO₂ [Ar: C, 12; O, 16; Ca, 40]

1. (a) Calculate the number of moles of calcium carbonate in 25.0 g. [1]
2. (b) Calculate the mass of calcium oxide formed when 25.0 g of calcium carbonate is completely decomposed. [2]
3. (c) State one use of calcium oxide. [1]

Fe₂O₃ + 3CO → 2Fe + 3CO₂ [Ar: C, 12; O, 16; Fe, 56]

1. (a) Calculate the maximum mass of iron, in tonnes, that can be made from 8.0 tonnes of iron(III) oxide. [3]
2. (b) Calculate the mass of carbon monoxide needed to react with 8.0 tonnes of iron(III) oxide. [2]

2.4 g of magnesium is added to a solution containing 0.15 mol of hydrochloric acid.Mg + 2HCl → MgCl₂ + H₂ [Ar: Mg, 24; Cl, 35.5]

1. (a) Calculate the number of moles of magnesium in 2.4 g. [1]
2. (b) Show which reactant is in excess. [2]
3. (c) Calculate the mass of magnesium chloride formed. [2]

4.20 g of the carbonate of a Group II metal M is heated until there is no further change in mass. 2.00 g of the metal oxide remains.MCO₃ → MO + CO₂ [Ar: C, 12; O, 16]

1. (a) Calculate the mass of carbon dioxide given off and the number of moles of carbon dioxide. [2]
2. (b) Deduce the relative formula mass of MCO₃. [1]
3. (c) Deduce the relative atomic mass of M and identify M. [2]
4. (d) Check your answer by calculating the expected mass of the oxide MO. [1]

1. (a) What is the formula of aluminium sulfate?A AlSO₄B Al₂SO₄C Al₃(SO₄)₂D Al₂(SO₄)₃ [1]

1. (a) Balance the equation for the reduction of iron(III) oxide in a blast furnace:…Fe₂O₃ + …CO → …Fe + …CO₂ [1]
2. (b) Balance the equation for the complete combustion of propane, a gas in LPG cylinders:…C₃H₈ + …O₂ → …CO₂ + …H₂O [1]
3. (c) Write the balanced equation, with state symbols, for the reaction of magnesium with dilute hydrochloric acid. [2]

1. (a) Write the ionic equation, with state symbols, for the neutralisation of any acid by any alkali. [2]
2. (b) Aqueous silver nitrate is added to aqueous sodium chloride. Write the ionic equation, with state symbols, for the reaction. [2]
3. (c) Aqueous barium chloride is added to aqueous sodium sulfate. Write the ionic equation and name the spectator ions. [2]

1. (a) Write the formula of ammonium phosphate, which contains NH₄⁺ and PO₄³⁻ ions. [1]
2. (b) Write the formula of iron(III) hydroxide. [1]
3. (c) Write the formula of calcium nitrate. [1]
4. (d) Calcium carbonate reacts with dilute nitric acid. Write a balanced symbol equation for the reaction. [2]

1. (a) Zinc powder is added to copper(II) sulfate solution. Write the ionic equation, with state symbols, for the reaction. [2]
2. (b) Identify the spectator ion in (a). [1]
3. (c) Chlorine gas is bubbled into aqueous potassium bromide. Write the ionic equation. [2]
4. (d) Write the ionic equation for the reaction of any carbonate ion with dilute acid. [2]

1. (a) What is the volume of 0.25 mol of oxygen gas at room temperature and pressure? [molar volume = 24 dm³ at r.t.p.]A 0.25 dm³B 6.0 dm³C 24 dm³D 96 dm³ [1]

Mg + 2HCl → MgCl₂ + H₂ [Ar: Mg, 24; one mole of any gas occupies 24 dm³ at r.t.p.]

1. (a) Calculate the number of moles of magnesium in 0.48 g. [1]
2. (b) Calculate the volume of hydrogen, in cm³, formed at room temperature and pressure when 0.48 g of magnesium reacts with excess acid. [2]

50 cm³ of methane from a Sui gas supply is burned completely in 150 cm³ of oxygen. All volumes are measured at room temperature and pressure.CH₄ + 2O₂ → CO₂ + 2H₂O

1. (a) Calculate the volume of oxygen that reacts with 50 cm³ of methane. [1]
2. (b) Calculate the volume of carbon dioxide formed. [1]
3. (c) Calculate the total volume of gas left at the end, measured at room temperature and pressure, and state what it contains. [2]

A hair-bleach solution contains hydrogen peroxide. 50.0 cm³ of the solution is completely decomposed using a little manganese(IV) oxide. 180 cm³ of oxygen is collected at room temperature and pressure.2H₂O₂ → 2H₂O + O₂

1. (a) Calculate the number of moles of oxygen produced. [1]
2. (b) Calculate the concentration of the hydrogen peroxide solution in mol/dm³. [3]
3. (c) Calculate the concentration in g/dm³. [Mr: H₂O₂, 34] [1]
4. (d) State the role of the manganese(IV) oxide. [1]

A sample of a hydrocarbon contains 2.4 g of carbon and 0.6 g of hydrogen. [Ar: H, 1; C, 12]

1. (a) Calculate the empirical formula of the hydrocarbon. [2]
2. (b) The relative molecular mass is 30. Deduce the molecular formula. [1]

1. (a) An oxide of iron found in a red soil sample from Balochistan contains 70.0% iron by mass. Calculate its empirical formula. [Ar: O, 16; Fe, 56] [3]
2. (b) Deduce the oxidation number of iron in this oxide. [1]

Washing soda is hydrated sodium carbonate, Na₂CO₃·xH₂O. 5.00 g of washing soda is heated until all the water of crystallisation is removed. 1.85 g of anhydrous sodium carbonate remains. [Mr: Na₂CO₃, 106; H₂O, 18]

1. (a) Calculate the mass of water lost. [1]
2. (b) Calculate the number of moles of anhydrous sodium carbonate and of water. [2]
3. (c) Deduce the value of x. [1]

Compound Z, found in vinegar, contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass. [Ar: H, 1; C, 12; O, 16]

1. (a) Calculate the empirical formula of compound Z. [3]
2. (b) The relative molecular mass of Z is 60. Deduce its molecular formula. [2]
3. (c) Z turns blue litmus red and fizzes with sodium carbonate. Name Z. [1]

2Mg + O₂ → 2MgO [Ar: O, 16; Mg, 24]

1. (a) Calculate the maximum (theoretical) mass of magnesium oxide that 12.0 g of magnesium can form. [2]
2. (b) Only 17.0 g of magnesium oxide is collected. Calculate the percentage yield. [1]
3. (c) Suggest one reason why the yield is less than 100%. [1]

A 5.00 g sample of limestone from a quarry near Margalla Hills is added to excess dilute hydrochloric acid. 1.08 dm³ of carbon dioxide is collected at room temperature and pressure. The impurities do not react with the acid.CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂ [Mr: CaCO₃, 100; molar volume 24 dm³ at r.t.p.]

1. (a) Calculate the number of moles of carbon dioxide produced. [1]
2. (b) Calculate the mass of calcium carbonate in the sample. [2]
3. (c) Calculate the percentage purity of the limestone. [1]

A farmer near Sahiwal compares three nitrogen fertilisers: ammonium nitrate NH₄NO₃ (Mr 80), ammonium sulfate (NH₄)₂SO₄ (Mr 132) and urea CO(NH₂)₂ (Mr 60). [Ar: N, 14]

1. (a) Calculate the percentage by mass of nitrogen in each fertiliser. Give answers to 3 significant figures. [3]
2. (b) A farmer needs 70 kg of nitrogen for a field. Calculate the mass of urea needed. [2]
3. (c) Suggest one reason, other than nitrogen content, why a farmer might choose ammonium sulfate. [1]

1. (a) What is the relative formula mass, Mr, of hydrated copper(II) sulfate, CuSO₄·5H₂O? [Ar: H, 1; O, 16; S, 32; Cu, 64]A 160B 178C 250D 268 [1]

1. (a) Define relative atomic mass. [2]
2. (b) A sample of chlorine contains 75% chlorine-35 and 25% chlorine-37 atoms. Calculate the relative atomic mass of chlorine. [2]
3. (c) Calculate the relative formula mass of ammonium sulfate, (NH₄)₂SO₄, used as a fertiliser in Punjab. [Ar: H, 1; N, 14; O, 16; S, 32] [1]
4. (d) Calculate the relative formula mass of calcium nitrate, Ca(NO₃)₂. [Ar: N, 14; O, 16; Ca, 40] [1]