C4

• Acids


  Substances producing more hydrogen ions than hydroxide ions when dissolved in water
• Acidic solutions


  Solutions with a pH lower than 7
• Solution


  Mixture formed by a solute and a solvent
• Ion


  Electrically charged particle, formed when an atom or molecule gains or loses electrons
• Acids are sources of hydrogen ions, H+
• Acidic solutions have pH values less than 7
• Alkalis


  Substances producing more hydroxide ions than hydrogen ions when dissolved in water
• Alkaline solutions


  Solutions with a pH greater than 7
• Alkalis are sources of hydroxide ions, OH-
• Neutral solution


  A solution that is neither acidic nor alkaline, and has a pH of 7
• Indicators


  Substances that have different colours, depending upon the pH of the solution they are in
• pH scale


  Measures the acidity or alkalinity of a solution
• Acid


  Substance producing more hydrogen ions than hydroxide ions when dissolved in water
• Salt


  Substance formed when the hydrogen ion in an acid is replaced by a metal ion
• Ion


  Electrically charged particle, formed when an atom or molecule gains or loses electrons
• Metal


  Shiny element that is a good conductor of electricity and heat, and which forms basic oxides
• Reaction of acids with metals

  Acid + metal → salt + hydrogen
• Reaction of acids with metal oxides


  Acid + metal oxide → salt + water
• Reaction of acids with metal hydroxides

  Acid + metal hydroxide → salt + water
• Reaction of acids with carbonates

  Acid + carbonate → salt + water + carbon dioxide
• Metal oxides and metal hydroxides both react with acids to produce salts and water
• Limewater


  Calcium hydroxide solution. It turns milky in the presence of carbon dioxide
• Carbon dioxide turns limewater milky or cloudy white
• Indicators


  Used to determine whether a solution is acidic or alkaline
• Neutralisation


  The reaction between an acid and a base
• Base


  A substance that reacts with an acid to neutralise it and produce a salt and water
• Alkali


  A soluble base that dissolves in water to form an alkaline solution
• Copper oxide is a base, but not an alkali because it is insoluble in water
• Sodium hydroxide is a base and an alkali because it dissolves in water
• All alkalis are bases


  But not all bases are alkalis
• Neutralisation reaction


  Hydrogen ions from acid react with hydroxide ions from alkali to form water
• Pure water is neutral with a pH of 7
• A neutral solution can be produced if the correct amounts of acid and alkali react together
• Indicators


  Used to determine whether a solution is acidic or alkaline
• Reactions of acids


  Acids react with metals, bases and carbonates to produce salts
• Neutralisation


  The reaction between an acid and a base
• Solution


  Mixture formed by a solute and a solvent
• Solute


  The dissolved substance in a solution
• Dissolve


  When a substance breaks up and mixes completely with a solvent to produce a solution
• Solvent


  The liquid in which the solute dissolves to form a solution