chemical changes slides

• Acid Reactions

  • Acids + Reactive Metal
  • Acids + Base
  • Acids + Metal Carbonate
  • Salt + Hydrogen gas
  • Salt + Water
  • Salt + Water + Carbon dioxide
• Acids + Reactive Metal


  Acid + Reactive metal ⟶ Salt + Hydrogen gas
• Acids + Base


  Acid + Base ⟶ Salt + Water
• Acids + Metal Carbonate


  Acid + Metal Carbonate ⟶ Salt + Water + Carbon Dioxide
• Salt


  Formed when an acid reacts with a reactive metal, base, or metal carbonate
• Hydrogen gas


  Formed when an acid reacts with a reactive metal
• Carbon dioxide


  Formed when an acid reacts with a metal carbonate
• Bases and alkalis


  • Bases are metal oxides or metal hydroxides
  • Alkalis are bases which are soluble in water
  • Alkalis dissolve in water to produce an aqueous solution of hydroxide ions (OH-)
  • E.g. NaOH (sodium hydroxide)
• Acids


  Produce H+(aq) when dissolved in water
• Bases


  Produce OH-(aq) when dissolved in water
• Alkalis


  Bases which are soluble in water
• Neutralisation


  H+(aq) + OH-(aq) ⟶ H2O(l)
• Acid + Base


  Acid + Base ⟶ Salt + Water
• Acid + Metal Carbonate

  Acid + Metal Carbonate ⟶ Salt + Water + Carbon Dioxide
• Ammonium salts


  Ionic compounds which contain ammonium (NH4+) cations
• Base + Ammonium Salt


  Ammonium Salt + Base ⟶ Salt + Water + Ammonia
• Ammonia


  Formed when a base reacts with an ammonium salt
• The reactions we learnt produce 3 gases: Hydrogen gas (H2), Carbon dioxide (CO2), and Ammonia (NH3)
• Test for Hydrogen gas


  Insert a lighted splint into the test tube. Hydrogen gas extinguishes the burning splint with a squeaky 'pop' sound.
• Test for Carbon dioxide


  Bubble the gas through limewater. Carbon dioxide gas produces a white precipitate (an insoluble white solid) in limewater.
• Test for Ammonia


  Place a piece of moist red litmus paper at the mouth of the test tube. Ammonia gas turns damp red litmus paper blue. Note: Ammonia also has a strong, pungent odour.
• When an acid reacts with another reagent, the hydrogen of the acid is replaced by the metal of the other reagent to form a salt and other product(s).
• pH


  A measure of how acidic or alkaline a solution is, ranging from 0 to 14. A lower pH indicates a higher concentration of H+(aq) and more acidity.
• pH can be approximately determined using Universal indicator
• Whether a solution is acidic or alkaline can be quickly determined with litmus paper
• Acid Reactions


  • Acids
  • Acids + Reactive Metal
  • Acids + Base
  • Acids + Metal Carbonate
  • Salt + Hydrogen gas
  • Salt + Water
  • Salt + Water + Carbon dioxide