group 1 to 3

• GROUP I Cations

  • Lead (II), Mercury (I), Silver (I)

  • Group reagent: HYDROCHLORIC ACID (HCl)
• Reactions of lead(ll) ions: A solution of lead nitrate (0.25M) or lead acetate (0.25M) can be used for the study of these reactions
• GROUP II Cations

  • Mercury (ll), Bismuth (lIl), Copper (II), Cadmium(lI), Arsenic (III) and (V), Antimony (III) and (V), and Tin (ll) and (IV)
  • Group reagent: HYDROGEN SULFIDE (H2S) - in gas form or saturated aqueous solution
• GROUP II Cations

  • traditionally divided into two (2) subgroups: COPPER subgroup and ARSENIC subgroup
  • basis of this division is the solubility of the sulfide precipitates in ammonium polysulfide
  • COPPER subgroup - INSOLUBLE
  • ARSENIC subgroup - SOLUBLE; w/ the formation of thiosalts
• The reactions of mercury(II) ions

  • can be studied with a dilute solution of mercury(II) nitrate(0.05M)
  • All compounds of mercury are toxic!
• GROUP II Cations

  • Hydrogen sulfide - (gas or saturated aqueous solution) in the presence of dilute (M) hydrochloric acid, initially a white precipitate of mercury(II) chlorosulfide forms, which reacts with further amounts of hydrogen sulfide and finally a black precipitate of mercury(II) sulfide is formed:
• Reactions of copper (II) ions: These reactions can be studiedwith a 0.25M solution of copper(II) sulfate.

  1. Hydrogen sulfide (gas or saturated aqueous solution) black precipitate of copper (II) sulfide
  2. Sodium hydroxide - in cold solution blue precipitate of copper(II) hydroxide
• Reactions of bismuth(IIl) ions

  • these reactions can be studied with a 0.2 M solution of bismuth (III) nitrate, which contains about 3-4% nitric acid
  • Hydrogen sulfide (gas or saturated aqueous solution) -brown precipitate of bismuth sulfide
  • Sodium tetrahydroxostannate (II). First, the sodium hydroxide present in the reagent reacts with bismuth (III) ions, bismuth (III) hydroxide is then reduced by tetrahydroxostannate (II) ions to form bismuth metal and hexahydroxostannate (IV) ions
• Reactions of cobalt(II) ions: The reactions of cobalt (II)ions can be studied with a 0.5M solution of cobalt (II)chloride [CoCl2 · 6 H2O], or cobalt (II) nitrate [Co(NO3 )2 6H2O]

  1. Ammonium sulfide solution - black precipitate of cobalt (II) from neutral or alkaline solution
• Reactions of nickel(II) ions: For the study of these reactions use a 0.5M solution of nickel sulfate (NiSO4 · 7H2O), or nickel chloride (NiCI2 · 6 H2O).

  1. Ammonium sulfide solution - black precipitate of nickel sulfide from neutral or slightly alkaline solutions
  2. Sodium hydroxide solution - green precipitation of nickel(II) hydroxide
  3. Ammonia solution - green precipitate of nickel(II)hydroxide
• The Manganese (II) cations are derived from manganese(II) oxide. They form colorless salts, although if the compound contains water of crystallization, and in solutions they are slightly pink
• Reactions of manganese(II) ions: For the study of these reactions a 0.25M solution of manganese(II)chloride (MnCI2 · 4 H2O), or manganese (II) sulfate(MnSO4 · 4 H2O) can be used.

  1. Ammonium sulfide solution - pink precipitate of manganese (II) sulfide: Mn2+ + S2- ⇄ MnS ↓
  2. 2. Sodium hydroxide solution - a white precipitate of manganese (II) hydroxide: Mn2+ + 2 OH
• Zinc (Zn)

  • a bluish-white metal; it is fairly malleable and ductile at 110-150 °C. It melts at 410°C and boils at 906°C
  • Reactions of zinc(ll) ions: A 0.25M solution of zinc sulfate(ZnSO4 . 7 H2O) can be used to study these reactions.
  • 1. Ammonium sulfide solution - a white precipitate of zinc sulfide, ZnS, from neutral or alkaline solutions.Zn2+ +S2- ⇄ ZnS ↓
  • 2. Sodium hydroxide solution - white gelatinous precipitate of zinc hydroxide: