pH, acids and alkalis

Cards (10)

  • Blue litmus paper - test for acids (turns red)
  • Red litmus paper - test for alkalis (turns blue)
  • pH is a measure of the concentration of hydrogen ions in a solution
  • Universal Indicator (paper/liquid) turns blue with alkali, red with acid and green with neutral
  • An alkali is a soluble hydroxide, releases OH-(aq) (hydroxide) ions into solution when added to water e.g. sodium hydroxide
  • A base includes alkalis, can neutralize an acid. Metal oxides and metal hydroxides are bases e.g. iron oxide, copper hydroxide
  • An acid releases H+(aq) (hydrogen) ions into solution when added to water
  • When an acid is neutralized it makes a compound called a salt
  • Salts:
    Hydrochloric acid -> metal chloride
    Nitric acid -> metal nitrate
    Sulfuric acid -> metal sulfate
  • General equations showing how acids can be neutralised
    1. Acid + base -> salt + water
    2. Acid + alkali -> salt + water
    3. Acid + metal -> salt + hydrogen
    4. Acid + metal carbonate -> salt + water + carbon dioxide