Amount of Substance (Edexcel International AS Chemistry)

The maximum permitted concentration of sulfur in diesel fuel is 10 mg of sulfur in 1 kg of diesel fuel.

A mass of 4.179 g of hydrated iron(III) sulfate, Fe₂(SO₄)₃·H₂O, was dissolved in deionised water and the solution made up to 200 cm^{3 .}

What is the concentration of sulfate ions, SO₄^2-, in the solution, in mol dm⁻³?

[Molar mass of Fe₂(SO₄)₃·H₂O = 417.9 g mol⁻¹]

A mass of 0.23 g of sodium was added to 350 cm³ water to form hydrogen and a solution of sodium hydroxide.

Na (s) + H₂O (l) → NaOH (aq) + 1⁄2H₂ (g)

2NaOH(aq) + MgSO₄(aq) → Mg(OH)₂(s) + Na₂SO₄(aq)

Which conversion has the lowest percentage atom economy (by mass) for the formation of CaCl₂?

The concentration of nitrogen dioxide in a sample of air is 0.5 ppm.
What is the percentage of nitrogen dioxide molecules in this sample of air?

The equation for the complete combustion of propan-1-ol is shown.

C₃H₇OH(l) + 4 1⁄2O2(g) → 3CO₂(g) + 4H₂O(l)

2.00 × 10⁻³ mol of propan-1-ol undergoes complete combustion.

What mass of carbon dioxide is formed?

A student is provided with 25.0 cm³ of 1.00 mol dm^–3 hydrochloric acid.

What volume of distilled water should the student add to this solution to make a 0.0500 mol dm^–3 solution?

Iron(III) oxide is reduced by hydrogen in a two-step process.

What is the maximum mass of iron that could be produced from 39.9 tonnes of Fe₂O₃ ?
[A_r values: H = 1.0 O = 16.0 Fe = 55.8]   

Which of these gases occupies 6.0 dm³ at room temperature and pressure (r.t.p.)?

[molar volume of gas at r.t.p. = 24.0 dm³ mol⁻¹

A_r values: He = 4.0 C = 12.0 N = 14.0 O = 16.0]

How many moles are there in 15.1 cm³ of liquid propan-1-ol?

[Density of propan-1-ol = 0.80 g cm⁻³      M_r of propan-1-ol = 60]

Which of these solutions contains the greatest number of ions?

What volume, in dm³, of hydrogen gas will be produced when 3.00 g of lithium is reacted with water at room temperature and pressure (r.t.p.)?

2Li + 2H₂O → 2LiOH + H₂

[Molar volume of gas at r.t.p. = 24.0 dm³ mol^–1]

Potassium chlorate(V) decomposes on heating to form oxygen.

2KClO₃ → 2KCl + 3O₂

What is the atom economy (by mass) for the formation of oxygen?
[A_r values: O = 16.0 Cl = 35.5 K = 39.1]

10.00 g of hydrated magnesium sulfate, MgSO₄•7H₂O, is heated to remove the water of crystallisation.

What mass of anhydrous magnesium sulfate, MgSO₄, is formed?

[Molar mass of MgSO₄•7H₂O = 246.4 g mol⁻¹ ]

Propane burns completely in oxygen as shown.

C₃H₈ (g) + 5O₂ (g) → 3CO₂ (g) + 4H₂O (l)

100 cm³ of propane was mixed with 600 cm³ of oxygen and the mixture was ignited.

What is the total volume, in cm³, of the gas mixture at the end of the reaction?

All gas volumes were measured at room temperature and pressure.

Barium chloride solution, BaCl₂ (aq), reacts with gallium sulfate solution, Ga₂(SO₄)₃ (aq) to form a precipitate of barium sulfate, BaSO₄ (s).

What is the minimum volume of 0.100 mol dm⁻³ barium chloride needed to precipitate all the sulfate ions in 200 cm³ of 0.05 mol dm⁻³ gallium sulfate?

Which aqueous solution contains the greatest number of ions?

Which aqueous solution has the highest concentration, in mol dm^-3, of chloride ions?

A 4.00 mol dm⁻³ solution of an acid is used to prepare dilute solutions of the acid.

What volume of water is required to make up 150 cm³ of 0.35 mol dm⁻³ solution of the acid?