Chemical changes

    Cards (41)

    • What is oxidation in terms of oxygen gain?
      Oxidation is when a substance gains oxygen.
    • What is reduction in terms of oxygen loss?
      Reduction is when a substance loses oxygen.
    • What is the reactivity series of metals and its trends?
      • Metals are arranged in order of reactivity.
      • Metals above H2 react with acids to produce H2.
      • More reactive metals react quicker and more violently with acids.
      • Metals below H2 do not react with acids.
      • Mostly Group I and II metals react with water; Aluminium is a borderline case.
    • What is a displacement reaction?
      A displacement reaction is when a more reactive metal displaces a less reactive metal from a compound.
    • How are unreactive metals found in the Earth?
      Unreactive metals are found in their natural state.
    • How can metals less reactive than carbon be extracted?
      They can be extracted by reduction with carbon.
    • How are metals more reactive than carbon extracted?
      They are extracted by electrolysis.
    • How are oxidation and reduction defined in terms of electron transfer?
      Oxidation is the loss of electrons, and reduction is the gain of electrons.
    • What is the general equation for a reaction between metals and acids?
      The equation is Metal + acid → salt + hydrogen.
    • What type of reaction occurs when metals react with acids?
      It is a redox reaction and also a displacement reaction.
    • Which metals in the reactivity series will react with acid?
      Those metals above hydrogen will react with acid.
    • What is the general equation for a neutralisation reaction?
      The equation is Base + acidsalt + water.
    • What is the general equation for the reaction between metal carbonate and acid?
      The equation is Metal carbonate + acid → salt + water + carbon dioxide.
    • What is the general equation for the reaction between metal oxides and acids?
      The equation is Metal oxide + acid → salt + water.
    • What is a redox reaction?
      A redox reaction is a reaction where both oxidation and reduction occur.
    • In the reaction between magnesium and hydrochloric acid, which species is oxidised and which is reduced?
      Magnesium is oxidised (loses electrons), and hydrogen is reduced (gains electrons).
    • How is a soluble salt formed?
      1. React excess acid with an insoluble chemical (e.g., metal oxide).
      2. Filter off the leftovers.
      3. Crystallise the product.
    • What do acids produce in aqueous solutions?
      Acids produce hydrogen ions.
    • What do alkalis produce in aqueous solutions?
      Alkalis produce hydroxide ions.
    • What are bases, acids, and alkalis?
      • Bases neutralise acids.
      • Acids produce hydrogen ions in aqueous solutions.
      • Alkalis are soluble bases that produce hydroxide ions in aqueous solutions.
    • What is the pH scale and what does a pH of 7 indicate?
      The pH scale measures acidity/alkalinity; a pH of 7 indicates a neutral solution.
    • What is the short ionic equation for a neutralisation reaction?
      The equation is H+ + OH−H2O.
    • What is a strong acid?
      A strong acid is completely ionised in aqueous solution.
    • What is a weak acid?
      A weak acid is only partially ionised in aqueous solution.
    • What happens to pH as the concentration of H+ increases?
      The pH decreases as the concentration of H+ increases.
    • What does a pH of 7 indicate about a solution?
      It indicates a neutral solution.
    • What defines a strong acid?
      A strong acid is completely ionised in aqueous solution.
    • What defines a weak acid?
      A weak acid is only partially ionised in aqueous solution.
    • What is the difference between concentrated and dilute acids?
      • Concentrated acid has more moles of acid per unit volume than dilute.
      • Dilute refers to solutions of low concentrations.
      • Concentration is not the same as strength.
      • Strength refers to complete ionisation (strong) or partial ionisation (weak).
    • What change occurs in hydrogen ion concentration as the pH decreases by one unit?
      It increases by a factor of 10.
    • What is electrolysis?
      It is the passing of an electric current through ionic substances to break them down into elements.
    • What is an electrolyte?
      An electrolyte is a liquid or solution that conducts electricity.
    • What is the cathode in electrolysis?
      The cathode is the negative electrode.
    • What is the anode in electrolysis?
      The anode is the positive electrode.
    • What occurs at the cathode during electrolysis?
      Reduction occurs at the cathode.
    • What occurs at the anode during electrolysis?
      Oxidation occurs at the anode.
    • In aqueous electrolysis, what is discharged at the cathode?
      The less reactive element is discharged at the cathode.
    • What is produced at the anode during aqueous electrolysis unless halide ions are present?
      Oxygen is produced at the anode unless halide ions are present.
    • How is aluminium manufactured?
      Aluminium is made through the electrolysis of aluminium oxide and cryolite.
    • Why is the process of aluminium manufacturing expensive?
      It requires a lot of energy to produce the current in electrolysis.
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