Qualitative Analysis CAPE Unit 1 Chemistry PDF

Qualitative Analysis CAPE Unit 1 Chemistry Mrs. K G-Ramnarine  Objectives Identify cations: K+, Na+, Ca2+, Ba2+, Cu2+, by their flames tests by referring to atomic emissions Identify Mg2+, Al3+, Ca2+, Cr3+, Mn2+, Fe2+, Fe3+, Cu2+, Zn2+, Ba2+, P...

Qualitative Analysis CAPE Unit 1 Chemistry Mrs. K G-Ramnarine  Objectives Identify cations: K+, Na+, Ca2+, Ba2+, Cu2+, by their flames tests by referring to atomic emissions Identify Mg2+, Al3+, Ca2+, Cr3+, Mn2+, Fe2+, Fe3+, Cu2+, Zn2+, Ba2+, Pb2+, NH4+, including the reactions with OH-, CO32- and NH43 and confirmatory tests Explain the principles upon which the reactions above are based, refer to equilibrium concepts and basic, amphoteric and complexation Write ionic equations for the equations above Identify anions CO32-, NO3-, SO42-, SO32-, Cl-, Br-, I-, CRO4- Write ionic equations for the reactions above IGCSE Lab: Flame tests for metal ions - YouTube Metal Flame test Potassium lilac Sodium Bright orange-yellow Calcium Brick red Barium pale/apple green Copper II Blue green with non- halide Blue with halide CATION Colour in Nitric acid if not soluble in water Cr3+ Violet Cu2+ Blue Fe2+ Pale green/violet Fe3+ Yellow-brown Mn2+ Pale pink  Recap solubility Taken from: Chemistry for CSEC – Anne Tindale  In NaOH(aq) In NH3(aq) ppt In excess ppt In excess Mg2+ white insoluble white insoluble Al3+ white soluble white insoluble Identification of cations Ca2+ white insoluble - Pb2+ white soluble white insoluble Zn2+ white soluble white soluble with NaOH and NH3 Cr3+ Grey-green soluble Grey-green insoluble Mn2+ Off-white insoluble Off-white insoluble Fe2+ Dirty green insoluble Dirty green insoluble Fe3+ Red-brown insoluble Red-brown insoluble Cu2+ Pale blue insoluble blue soluble Ba2+ No ppt No ppt - NH4+ No ppt- NH3 evolves -  In CO32- notes equations Mg2+ white No gas evolved M2+aq) + CO32-(aq) →MCO3(s) Al3+ white CO2(g) evolved * Ca2+ white No gas evolved M2+aq) + CO32-(aq) →MCO3(s) Pb2+ white No gas evolved M2+aq) + CO32-(aq) →MCO3(s) Identification Zn2+ Cr3+ white Dirty green No gas evolved M2+aq) + CO32-(aq) →MCO3(s) * of cations Mn2+ Fe2+ white Dirty green Ppt turns quickly brown M2+aq) + CO32-(aq) →MCO3(s) M2+aq) + CO32-(aq) →MCO3(s) with Na2CO3 Fe3+ Red-brown * Cu2+ Light blue ppt * Ba2+ white No gas evolved M2+aq) + CO32-(aq) →MCO3(s) NH4+ No ppt, NH3 gas evolved *  To confirm Pb2+ and distinguish from Add KI or K2CrO4 – bright yellow Al3+ ppt, insoluble To confirm presence of Mn2+ Mn2+ oxidised to Mn7+(MnO4-) in sodium bismuthate (NaBiO3) Purple to pink colour change Other indicates positive test confirmatory Distinguish between Fe2+ and Fe3+ Fe3+ + thiocyanate io (NH4SCN) tests produces blood red [Fe(SCN)2+) To confirm Cr3+ Reacts with [Fe(CN)64-] to give green insoluble [Cr[Fe(CN)6] To confirm Zn2+ Reacts with [Fe(CN)64-] to give yellow-white soluble [Zn2[Fe(CN)6]  HCl(aq) Conc. H2SO4(aq) CO32- CO3 2−(s) + 2H+(aq) → H2O(l) + CO2(g) CO3 2−(s) + 2H+(aq) → H2O(l) + CO2(g) SO32- SO3 2−(aq) + 2H+(aq) → SO2(g) + H2O(l) - NO3- - NO3 −(s) + H2SO4(l) → HNO3(g) + HSO4 −(aq) 4HNO3(g) → 2H2O(l) + 4NO2(g) + O2(g) 4HNO3(g) + Cu(s) → Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l) CrO42- 2H+(aq) + 2CrO4 2−(aq) → Cr2O72-(aq) + H2O(l) - Yellow-orange Cl- - H2SO4(l) + Cl−(s) → HCl(g) + HSO4 −(aq) Br- - H2SO4(l) + Br−(s) → HBr(g) + HSO4 −(aq) 2HBr(g) + [O] → Br2(s) + H2O(l) I- - H2SO4(l) + I−(s) → HI(g) + HSO4 −(aq) 2HI(g) + [O] → I2(s) + H2O(l) Deep purple ppt to dark purple vapour Identification of anions  + 2+ 2+ Ag (aq) followed by aqueous With Pb With Ba ammonia CO32- 2Ag+(aq) + CO32−(aq) → Ag2CO3(s) Pb2+(aq) + CO3 2−(aq) → PbCO3(s) Ba2+(aq) + CO3 2−(aq) → BaCO3(s) SO42- - Pb2+(aq) + SO4 2−(aq) → PbSO4(s) Ba2+(aq) + SO4 2−(aq) → BaSO4(s) SO32- - Pb2+(aq) + SO3 2−(aq) → PbSO3(s) Ba2+(aq) + SO3 2−(aq) → BaSO3(s) NO2- - - - CrO42- 2Ag+(aq) + CrO4 2−(aq) → Pb2+(aq) + CrO4 2−(aq) → PbCrO4(s) Ba2+(aq) + CrO4 2−(aq) → BaCrO4(s) Ag2CrO4(s) yellow Pale yellow Orange yellow Cl- Ag+(aq) + Cl−(aq) → AgCl(s) Pb2+(aq) + 2Cl−(aq) → PbCl2(s) - Br- Ag+(aq) + Br−(aq) → AgBr(s) Pb2+(aq) + 2Br−(aq) → PbBr2(s) - Off-white I- Ag+(aq) + I−(aq) → AgI(s) Pb2+(aq) + 2I−(aq) → PbI2(s) PbI2(s) + 2I−(aq) Note: where colours are not stated will be white yellow → [PbI4]2−(aq) yellow Identification of anions Taken from: Chemistry for CSEC – Anne Tindale  Testing for gases Taken from: Chemistry for CSEC – Anne Tindale