acids, bases + salts

acids, bases + salts

1. salts are made when an acid reacts with a base, carbonate or metal

   • the name of the salt formed depends on the metal in the base and the acid used
     • e.g. salts made using hydrochloric acid are called chlorides

2. acids

   • substances with a pH of less than 7
   • the more strongly acidic the solution, the lower its pH number
   • turns blue litmus paper red
   • turn universal indicator paper red if they are strongly acidic, or orange or yellow if they are weakly acidic

3. bases

   • substances that can react with acids + neutralise them to make a salt + water
   • usually metal oxides or metal hydroxides
     • e.g. copper oxide and sodium hydroxide are bases

4. alkalis

   • bases than dissolve in water
   • copper oxide is not an alkali because it DOES NOT dissolve in water
   • sodium hydroxide is an alkali because it DOES dissolve in water
   • pH of more than 7
     • the stronger the alkali, the higher the pH number
   • turn red litmus paper blue
   • turn universal indicator paper dark blue or purple

5. neutral solutions

   • have a pH of 7
   • do not change the colour of litmus paper
   • turn universal indicator green
   • e.g. water