notes so far

• 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