Chemistry

• • To make sure the cation is copper:
  • 1-Add drops of NaOH: blue precipitate
  • 2-Add excess of NaOH: insoluble- blue precipitate
• • To make sure the cation is copper:
  • 1-Add drops of NH4OH: Blue precipitate
  • 2-Add excess of NH4OH: soluble- dark blue solution
• • To make sure the cation is chromium:
  • 1-Add drops of NH4OH: green precipitate
  • 2-Add excess of NH4OH: insoluble-green precipitate
• • To make sure the cation is Iron(II):
  • 1-Add drops of NH4OH: green precipitate
  • 2-Add excess of NH4OH: insoluble-green precipitate
• • To make sure the cation is Iron(III):
  • 1-Add drops of NH4OH: red-brown precipitate
  • 2-Add excess of NH4OH: insoluble- red-brown precipitate.
• • To make sure the cation is Calcium:
  • 1-Add drops of NH4OH: no precipitate
  • 2-Add excess of NH4OH: no precipitate
• • To make sure the cation is Zinc:
  • 1-Add drops of NH4OH: white precipitate
  • 2-Add excess of NH4OH: soluble-colourless solution
• • To make sure the cation is aluminium:
  • 1-Add drops of NH4OH: white precipitate
  • 2-Add excess of NH4OH: insoluble- white precipitate
• • To make sure the cation is Iron(II):
  • 1-Add drops of NaOH: green precipitate
  • 2-Add excess of NaOH: insoluble-green precipitate
• • To make sure the cation is Chromium:
  • 1-Add drops of NaOH: green precipitate
  • 2-Add excess of NaOH: soluble-deep green solution
• • To make sure the cation is iron(III):
  • 1-Add drops of NaOH: red-brown precipitate
  • 2-Add excess of NaOH: insoluble red-brown precipitate
• • To make sure the cation is Calcium:
  • 1-Add drops of NaOH: white precipitate
  • 2-Add excess of NaOH: insoluble-white precipitate
• • To make sure the cation is aluminium:
  • 1-Add drops of NaOH: white precipitate
  • 2-Add excess of NaOH: solyble-colourless solution
• • To make sure the cation is zinc:
  • 1-Add drops of NaOH: white precipitate
  • 2-Add excess of NaOH: soluble-colourless solution
• • To make sure the cation is NH4 :
  • Add NaOH then heat gently then use damp red litmus paper
  • results: NH3 pungent gas turns damp red litmus paper into blue
• • To make sure the cation is NO3:
  • Add NaOH+ aluminium powder then heat gently then use damp red litmus paper
  • results: NH3 pungent gas turns damp red litmus paper into blue
• • To make sure the anion is CO3
  • Add dilute HNO3 then pass the gas through lime water
  • results: lime water turns milky
• • To make sure the anion is SO3:
  • Add dilute HCL then pass the gas through acidified potassium manganate(VII)
  • results: bubbles of SO2 gas which turns acidified KMnO4 from purple to colourless
• • To make sure there is Cl ion :
  • Add dilute HNO3 then add AgNO3
  • results: white precipitate
• • To make sure there is Br ion :
  • Add dilute HNO3 then add AgNO3
  • results: cream precipitate
• • To make sure there is I ion :
  • Add dilute HNO3 then add AgNO3
  • results: yellow precipitate
• • To make sure there is SO4 ion :
  • Add dilute HNO3 then add BaNO3
  • results: white precipitate