C4-Chemical changes

• Metal + Oxygen 


  = Metal oxide (oxidation)
• Metal + Water


  = Metal hydroxide
• If the metal is more reactive than hydrogen,it will displace it in a reaction of a compound.
• What will happen when copper oxide is reacts with aluminium?

  The aluminium will displace the copper as the copper bubbles and releases energy,which then results in aluminium oxide with copper in it’s pure elemental form.
• What will happen if sodium reacts with iron hydroxide?

  The sodium would displace the iron to form Sodium hydroxide and hydrogen.
• What would happen if zinc reacts with magnesium hydroxide?

  No reaction would occur as magnesium is more reactive than zinc so it cannot be displaced.
• How can we test for hydrogen within a metal hydroxide?

  Squeaky pop test- metal is ignited and if it ’pops’,there is hydrogen present.
• What does MASH stand for?

  metal + acid = salt + hydrogen
• What would happen if sodium reacted with hydrochloric acid?

  The sodium would displace the hydrogen in the acid by forming a salt (ionic compound) with chloride,and hydrogen resumes its elemental form.
• What are the three main acids and their salt products?

  Hydrochloric acid(HCl)=metal sulphate

  Sulphuric acid(H2SO4)=metal sulphate

  Nitric acid(HNO3)=metal nitrate
• What would the reaction between zinc and iron nitrate produce?

  Zinc displaces iron to produce zinc nitrate
• Metal carbonate + acid

  =salt + water + CO2
• How can an acid be produced?

  Through a non-metal oxide dissolving in water.
• What other features does an acid have?

  -Less than 7 pH (the lower pH the stronger the acid)

  -Releases H+ ions (the lower pH the less H+ ions)

  -Corrode metals

  -Neutralised by bases
• What are bases?

  Substances that neutralise acids and have a pH highter than 7.
• What is the difference between an insoluble and a soluble base?

  Insoluble bases=metal oxides/carbonates,cannot dissolve in water easily so it is hard to determine their pH.

  Soluble bases=metal hydroxides,are also known as alkalis.
• What does the pH scale measure and how does it work?

  The pH scale measures the acidity of a substance and can determine how strong an acid is by identifying how many H+ ions it realeases (more released=stronger acid).
• Which electrode do metals and non-metals go to?


  -Metals go to the cathode (cation to cathode)

  -Non metals go to the anode (anion to anode)
• What is the half equation formed at the cathode in the electrolysis of an aqueous solution?


  If the cation is less reactive than hydrogen:

  (cation)+e- --->(element)

  If the cation is more reactive than hydrogen:

  2H+ + 2e- ---> H2
• What is the half equation formed at the anode of the electrolysis of an aqueous solution?


  OH- ---> H20 + O2 + e-

  If the anion is a halide anion:

  (anion) ---> (element)+e-
• The strength of an acid depends on how well it ionises (dissociates) when added to water.
• Why is cryolite used in the electrolysis of aluminium oxide?

  Lowers melting point of aluminium so that less energy needs to be used, lowering costs.
• What is formed at each electrode in the electrolysis of aluminium xide?

  -Anode: Oxygen forms

  -Cathode: Aluminium forms
• Electrolysis of aqueous solutions

  -Aqueous solutions are dissolved in water

  -Water molecules ionise and form hydrogen and hydroxide ions
• What forms at the cathode during the electrolysis of an aqueous solution?

  Hydrogen is produced unless the metal is less react than hydrogen. (more reactive metal ions want to stay within the solution)
• What forms at the anode during the electrolysis of an aqueous solution?

  Oxygen is formed unless the anions are halides.