Chemical Changes

• What’s the pH scale?

  Measure of acidity/alkalinity of a solution
• What is considered an alkaline ?

  A pH above 7
• What is considered an acid ?

  A pH lower than 7
• What is considered neutral ?

  pH 7
• How To measure the pH of a solution?

  Using a universal indicator, or a pH probe attacked to a pH meter
• What ions do acids form?

  Hydrogen ions (H+)
• What ions do alkalis form?

  Hydroxide ions OH-
• What is the neutralisation reaction?

  acid + base -> salt + water

  or

  H+ + OH- -> H20
• What are metal oxides?

  Are bases, perform an oxidation reaction because the metals gain oxygen
• How are metals ordered in the reactivity series?

  By their reactions with water and dilute acids
• How do metals react with water?

  Metal + water -> metal hydroxide + hydrogen
• What is the reactivity series?

  How well a metal reacts, the higher up the reactivity series the more easily they form positive ions (reacts more easily with acid or water)
• How can a metal be extracted from oxides?

  Oxidation is the gain of oxygen,

  Reduction is the loss of oxygen
• How can some metals be extracted by carbon?

  if the metals are below carbon on the reactivity series, there is a reduction reaction using carbon.

  Metals higher than carbon have to be extracted using electrolysis
• What is oxidisation in terms of electrons?

  Loss of electrons.
• What is reduction in terms of electrons?

  Gain of electrons
• How do acids react with metals?

  Acid + metal oxide -> salt+ water
• What does hydrochloric acid produce?

  Chlorides
• What does nitric acid produce?

  Nitrates
• What does sulfuric acid produce?

  Sulfates
• How can soluble salts be made?

  From acids by reacting them with solid insoluble substances
• Whats a strong acid?

  completely ionised in aqueous solution
• What’s a weak acid?

  Partially ionised in aqueous solution
• What’s dilute?

  Contains a relatively small amount of a dissolved solute in a given volume
• What’s concentrated ?

  A substance with a high amount of solute in a solvent.
• What does electrolysis mean?

  The splitting up with electricity
• What ions move towards the cathode?

  Positive ions - reduction
• What ions move towards the anode

  ?

  negative ions - oxidisation
• What is the process of electrolysis?

  an electric current is passed through an electrolyte (a molten or dissolved ionic compound) , the ions move towards the electrodes where they react and the compound decomposes
• What’s electrolysis of molten ionic compounds?

  Simple ionic compound is electrolysed in the molten state using inert electrodes, the metal is produced at the cathode and the non-metal is produced at the anode
• What can metals be extracted from?

  Their ores
• What method is used to extract metals from ores?

  Electrolysis
• What is required to melt the ore during extraction?

  A significant amount of energy
• What is aluminum extracted from?

  Bauxite ore
• What does bauxite ore contain?

  Aluminum oxide
• What is the melting point of aluminum oxide?

  Very high
• What is mixed with aluminum oxide to lower its melting point?

  Cryolite
• What does cryolite do in the extraction process?

  Lowers the melting point
• What does the molten mixture contain?

  Free ions
• What do free ions in the molten mixture do?

  Conduct electricity