notes so far

Cards (27)

  • pH scale
    Measure of how acidic or alkaline a solution is
  • Lower pH
    More acidic solution
  • Higher pH

    More alkaline solution
  • Neutral substance has a pH of 7
  • Indicator
    Dye that changes colour depending on whether it's above or below a certain pH
  • Universal indicator
    • Contains a mixture of dyes which means they gradually change colour over a broad range of pH
  • pH probe
    Attached to a pH meter, dipping the probe into a solution allows electronic measurement of the pH
  • Advantages of pH probe
    • More accurate and precise than an indicator, as it doesn't involve humans guessing shades or particular colours
  • Acid
    Substance that forms aqueous solutions with a pH less than 7, producing hydrogen ions (H+) in water
  • Base
    Substance with a pH greater than 7, forming OH- ions in water
  • Alkali
    Base that dissolves in water to form a solution with a pH greater than 7
  • Neutralisation reaction
    Acid + Base → Salt + Water
  • Neutralisation products should be neutral
  • Strong acids
    • Ionise completely in water, all acid particles dissociate to release H+ ions
  • Weak acids
    • Do not fully ionise in solution, only a small portion of acid particles dissociate to release H+ ions, the ionisation is a reversible reaction
  • Higher concentration of H+ ions
    Faster rate of reaction, so strong acids are more reactive than weak acids of the same concentration
  • Acid strength
    Proportion of acid molecules that ionise in water
  • Acid concentration
    Amount of acid in a certain volume of water
  • pH scale ranges from 0 to 14
  • Reaction of metal oxides with acids
    Metal oxide + Acid → Salt + Water
  • Reaction of metal hydroxides with acids
    Metal hydroxide + Acid → Salt + Water
  • Reaction of metal carbonates with acids
    Metal carbonate + Acid → Salt + Water + Carbon dioxide
  • Reactivity series
    List of metals in order of their reactivity towards other substances, determined by how easily they lose electrons to form positive ions
  • Higher up the reactivity series
    More easily the metal reacts with water or acid
  • Reaction of metals with acids
    Acid + Metal → Salt + Hydrogen
  • Reactive metals react explosively with acids, less reactive metals react less violently, copper normally won't react with cold, dilute acids</b>
  • Reaction of metals with water

    Metal + Water → Metal hydroxide + Hydrogen