Chemical changes

• What do metals produce when they react with oxygen?

  Metal oxides
• Why are the reactions of metals with oxygen classified as oxidation reactions?

  Because the metals gain oxygen
• What should students be able to explain regarding reduction and oxidation?

  In terms of loss or gain of oxygen
• How is the reactivity of a metal related to its tendency to form positive ions?

  More reactive metals tend to form positive ions more readily
• What metals are included in the reactivity series?


  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Zinc
  • Iron
  • Copper
• What happens when a more reactive metal is placed in a compound with a less reactive metal?

  The more reactive metal can displace the less reactive metal
• What reactions should students recall regarding specific metals with water or dilute acids?

  Reactions of potassium, sodium, lithium, calcium, magnesium, zinc, iron, and copper
• How does the reactivity of metals with water or dilute acids relate to their tendency to form positive ions?

  More reactive metals form positive ions more easily
• What is the limitation regarding the reactions of metals with water and acids in this context?

  They are limited to room temperature and do not include reactions with steam
• What is the state of unreactive metals like gold in the Earth?

  They are found as the metal itself
• How can metals less reactive than carbon be extracted from their oxides?

  By reduction with carbon
• What does reduction involve in terms of oxygen?

  Loss of oxygen
• What knowledge is limited to regarding the reduction of oxides?

  Reduction using carbon
• What should students be able to identify in terms of oxidation and reduction?

  The substances which are oxidised or reduced in terms of gain or loss of oxygen
• What is oxidation in terms of electrons?

  Loss of electrons
• What is reduction in terms of electrons?

  Gain of electrons
• What should students be able to write for displacement reactions?

  Ionic equations
• What do acids produce when they react with some metals?

  Salts and hydrogen
• How are these reactions classified in terms of electrons?

  As redox reactions
• Which metals should students know the reactions of with hydrochloric and sulfuric acids?

  Magnesium, zinc, and iron
• What happens during neutralization reactions between acids and bases?

  • Acids are neutralised by alkalis and bases to produce salts and water
  • Acids react with metal carbonates to produce salts, water, and carbon dioxide
• What determines the particular salt produced in a reaction between an acid and a base or alkali?

  The acid used and the positive ions in the base, alkali, or carbonate
• What should students be able to predict from given reactants?

  The products of the reaction
• How can soluble salts be made from acids?

  By reacting them with solid insoluble substances
• What is the process to produce a solution of salt from an acid?

  Add solid to the acid until no more reacts and filter off the excess
• What can be done to produce solid salts from salt solutions?

  Crystallisation
• What is the required practical for preparing a pure, dry sample of a soluble salt?

  Using a Bunsen burner to heat dilute acid and evaporate the solution
• What do acids produce in aqueous solutions?

  Hydrogen ions (H+)
• What do aqueous solutions of alkalis contain?

  Hydroxide ions (OH–)
• What is the pH scale a measure of?

  The acidity or alkalinity of a solution
• What is the pH value of a neutral solution?

  7
• What pH values do aqueous solutions of acids and alkalis have?

  Acids have pH values less than 7, alkalis have pH values greater than 7
• What happens in neutralisation reactions between an acid and an alkali?

  Hydrogen ions react with hydroxide ions to produce water
• What is the purpose of using universal indicator or a pH probe?

  To measure the approximate pH of a solution
• What should students be able to do with the pH scale?

  Identify acidic or alkaline solutions
• What can be investigated regarding pH changes?

  When a strong acid neutralises a strong alkali
• What can be measured by titration?

  The volumes of acid and alkali solutions that react with each other
• What should students be able to describe regarding titrations?

  How to carry out titrations using strong acids and strong alkalis
• What calculations should higher tier students be able to perform in titrations?

  Calculate chemical quantities involving concentrations in $\text{mol/dm}^3$ and $\text{g/dm}^3$
• What characterizes a strong acid in aqueous solution?

  It is completely ionised