Paper 3, Higher

Describe Chadwick's contribution to the model of the atom.

Explain why polymers such as poly(ethene) are solid at room temperature.

Explain why the mass appears to decrease when a metal carbonate is heated in an open crucible.

Explain how to make a soluble salt from an acid and an alkali.

Describe an experiment to investigate the electrolysis of an aqueous solution using inert electrodes.

Explain what Bohr added to the nuclear model.

Explain the limitations of the particle model of states of matter.

Calculate the empirical formula of a compound containing 2.4 g of carbon and 0.6 g of hydrogen.

Write a balanced equation for the reaction of calcium carbonate with hydrochloric acid.

Explain the difference between a compound and a mixture, with an example of each.

How many atoms are in 0.5 moles of carbon? (Avogadro constant = 6.02 × 10²³)

Explain why ethanoic acid reacts more slowly with magnesium than hydrochloric acid of the same concentration.

Describe how to separate pure water from ink by distillation.

Calculate the mass of sodium hydroxide needed to make 250 cm³ of a 0.400 mol/dm³ solution. (Mr NaOH = 40)

Explain why the pH of acid falls when its concentration increases.

4.0 g of copper(II) oxide reacts with sulfuric acid. Calculate the maximum mass of copper(II) sulfate (Mr 159.5) that can be formed. (Mr CuO = 79.5) CuO + H₂SO₄ → CuSO₄ + H₂O

Explain what is meant by a limiting reactant and identify it when 2.4 g of magnesium reacts with 100 cm³ of 1.0 mol/dm³ HCl. Mg + 2HCl → MgCl₂ + H₂

Balance the equation: Fe₂O₃ + C → Fe + CO₂

Calculate the percentage by mass of nitrogen in ammonium nitrate, NH₄NO₃. (Ar N = 14, H = 1, O = 16)

Convert a concentration of 0.20 mol/dm³ of HCl into g/dm³. (Mr HCl = 36.5)

Calculate the volume of oxygen needed to burn 60 cm³ of methane completely. CH₄ + 2O₂ → CO₂ + 2H₂O

Describe how the plum pudding model of the atom was replaced by the nuclear model.

Describe how sodium and chlorine atoms form an ionic compound. You may use dot-and-cross diagrams.

Calculate the relative formula mass (Mr) of CaCO₃. (Relative atomic masses: Ca = 40, C = 12, O = 16)

Describe how to prepare a pure, dry sample of copper(II) sulfate crystals from copper(II) oxide and dilute sulfuric acid.

Predict the products at each electrode in the electrolysis of copper(II) chloride solution and write the half equation at the cathode.

Explain the difference between exothermic and endothermic reactions, with an example of each.

An atom of potassium has mass number 39 and atomic number 19. Give the numbers of protons, neutrons and electrons.

Explain why sodium chloride has a high melting point and conducts electricity when molten but not when solid.

What is the pH of a neutral solution?