(acids and bases)

• what do acids form in water?

  H+ ions
• what happens as the concentration of hydrogen ions increases?


  the pH decreases
• what happens the higher the concentration of hydrogen ions in a solution?

  the more acidic it is, so the lower the pH will be.
• what is a base?

  a substance that reacts with an acid to produce a salt and water.
• what is an alkali, in terms of bases?

  an alkali is a base that is soluble in water.
• what do alkalis form in water?

  OH- ions
• in alkaline solutions, what happens the higher the concentration of OH- ions?

  the higher the pH
• what colour does litmus turn in acidic solutions?

  red
• what colour does litmus turn in neutral solutions?

  Purple
• what colour does litmus turn in alkaline solutions?

  blue
• what colour does methyl orange turn in acidic solutions?

  Red
• what colour does methyl orange turn in neutral solutions?

  yellow
• what colour does methyl orange turn in alkaline solutions?

  Yellow
• what colour does phenolphthalein turn in neutral solutions?

  colourless
• what colour does phenolphthalein turn in acidic solutions?

  colourless
• what colour does phenolphthalein turn in alkaline solutions?


  pink
• what is the reaction between an acid and a base called?


  neutralisation
• what does a neutralisation reaction produce?

  salt and water
• neutralisation reactions in aqueous solutions can also be shown as what?

  an ionic equation in terms of H+ and OH- ions.
• what is an example of a neutralisation reaction?

  HCL + NaOH = NaCl + H2O