Acids and Alkali

• what is acid?


  a chemical which has a pH of less than 7 on the pH scale
• we can use pH-metres, pH paper and universal indicator drops to find the pH of something
• acids always contain hydrogen but that doesn't make it an acid.
• what is an alkali?


  a chemical which has a pH of more than 7 on the pH scale
• MASH?


  metals + acids -> Salt + Hydrogen
• Sulphuric Acid + Magnesium -> Magnesium Sulphate + Hydrogen
• how do we test for hydrogen in the lab?

  squeaky pop test!
• copper oxide + sulphuric acid -> copper sulphate + water
• magnesium oxide + nitric acid -> magnesium nitrate + water
• sodium oxide + chloric acid -> sodium chloride + water
• potassium oxide + nitric acid -> potassium nitrate + water
• CAWCS?


  carbonate, acid, water, CO2, salt
• blue litmus paper - used to identify acids and alkali. acids would go red
• cobalt chloride - used to test for presence of water. positive result would be the paper changing from blue to pink
• indicator - a special chemical that changes to a different colour in an acid or an alkali
• metal carbonate - a compound containing metal and oxygen atoms
• methyl orange - an indicator used to identify acids and alkalis where it would go red in presence of an acid and yellow/orange if alkali
• neutral - universal indicator goes green, pH of 7
• when a new substance is formed, its called a chemical change, often involving bubbling, fizzing, temp change, colour change, etc
• physical changes are more like when a change in state happens, which could include condensation, melting, evaporation, freezing, etc
• C6H12O6 is glucose