chemical change

Cards (37)

  • What is oxidation?
    loss of electrons
  • What is reduction?
    gain of electrons
  • What is the reactivity series of metals?
    The series shows the metals in order of their reactivity.
  • What are the trends in reactivities of metals in reactions with acids/water?
    Metal above H^2 in reactivity series react with acid to produce H^2. The more reactive the metal is, the quicker and more violent reaction with acid occurs

    Metals below H^2 don't react with acids

    Not all metals above H^2 react with water - mostly group one I and II metals. Aluminium us the borderline case
  • What is a displacement reaction?
    A reaction where a more reactive metal displaces a less reactive metal from a compound
  • How are unreactive metals found in Earth?
    In their natural state (well, they are unreactive)
  • How can metals less reactive than carbon be extracted?
    Reduction with carbon. Carbon displaces the metal in a metal oxide - gets oxidised to carbon oxides. Metal from the metal oxide gets reduced to the pure metal
  • How are metals more reactive than carbon extracted?
    By electrolysis
  • How are oxidation and reduction defined in terms of electron transfer?
    Oxidation -loss of electrons
    Reduction - gain of electrons
  • What is the general equation for a reaction between metals and acids? What type of reaction is this?
    Metal + acid ->salt + hydrogen
    Redox reaction, also a displacement reaction
  • Which metals in the reactivity series will react with acid
    Those above hydrogen
  • What is the general equation for a neutralisation reaction
    Base + acid -> salt + water
  • What is the general equation for the reaction between metal carbonate and acid
    Metal carbonate + acid -> salt + water + carbon dioxide
  • What is the general equation for the reaction between metal oxides and acid
    Metal oxide + acid -> a salt + water
  • What is a redox reaction?
    A reaction where both oxidation and reduction occurs
  • How is a soluble salt formed?
    a) React the excess acid with some insoluble chemical (e.g. metal oxide)
    b) Filter off the leftovers
    c) Crystallise the product
  • What do acids and alkalis produce in aqueous solutions?
    Acids produce hydrogen ions, alkalis produce hydroxide ions
  • What are bases?
    Bases are compounds that neutralise acids
  • What are acids?
    Acids produce hydrogen ions in aqueous solutions
  • What are alkalis?
    Alkalis are soluble bases - produce hydroxide ions in aqueous solution
  • What is the pH scale and what does a a pH of 7 show?
    The measure of acidity/alkalinity of a solution; neutral solution
  • What is a strong acid?
    A strong acid is completely ionised in aqueous solution. Examples of strong acids are hydrochloric, nitric and sulfuric acids.
  • What is a weak acid?
    A weak acid is only partially ionised in aqueous solution. Examples of weak acids are ethanoic, citric and carbonic acids.
  • What is a concentrated acid and what is a dilute acid?
    - Concentrated acid acid has more moles of acid per unit volume (dilute refers to solutions of low concentration)
  • Are concentrated and dilute acids the same as strong and weak acids?
    It is not the same - concentration is not the same thing as strength of an acid
    Strength refers to whether the acid is completely ionised in water (strong) or only partially (weak)
  • What is electrolysis
    The passing of an electric current through ionic substances that are molten or in solution to break down into elements; ions are discharge (they lose/gain electrons) to produce these
  • What is an electrolyte?
    The liquid/solution that conducts electricity
  • What is a cathode and what is an anode?
    Cathode is the negative electrode, anode is the positive electrode
  • What occurs at the cathode and what occurs at then anode during electrolysis?
    Reduction occurs at the cathode
    Oxidation occurs at the anode
  • How is aluminium manufactured?
    Aluminium is made through the electrolysis of aluminium oxide and cryolite
  • Why is the manufacture of aluminium expensive?
    Lots of energy is needed to produce the current in electrolysis which makes this process expensive
  • what happens to temperature in an exothermic reaction
    increases
  • what happens to temperature in endothermic
    it decreases
  • how do we extract metals less reactive then carbon
    extracted by reduction with carbon
  • how do we extract metals more reactive than carbon
    extracted using electrolysis
  • why can’t some metals be extracted by reduction
    1 some metals are more reactive than carbon
    2 some metals would react with carbon in the process
  • how is aluminium extracted
    electrolysis