Tests for Ions
- Created by: biahonrado
- Created on: 05-06-17 15:34
View mindmap
- tests for ions
- positive ions
- metal ions
- fill half a test tube with sample, add drop by drop to get results
- Cu2+
- with NH3(aq)/OH-(aq) = blue precipitate
- excess NH3 = precipitate dissolves to blue solution
- excess OH- = no change
- with NH3(aq)/OH-(aq) = blue precipitate
- Fe2+
- with NH3(aq)/OH- (aq) = green precipitate
- excess NH3 = no change
- excess OH- = no change
- with NH3(aq)/OH- (aq) = green precipitate
- Mn2+
- with NH3(aq)/OH-(aq) = brown precipitate
- excess NH3 = no change
- excess OH- = no change
- with NH3(aq)/OH-(aq) = brown precipitate
- Cr3+ (purple)
- with NH3(aq)/OH-(aq) = green precipitate
- excess NH3 = precipitate dissolves to give a purple solution
- excess OH- = precipitate dissolves to give a green solution
- with NH3(aq)/OH-(aq) = green precipitate
- Fe3+
- with NH3(aq)/OH-(aq) = brown precipitate
- excess NH3 = no change
- excess OH- = no change
- with NH3(aq)/OH-(aq) = brown precipitate
- ammonium ion, NH4+
- NH4+(aq) + OH-(aq) --> NH3(aq) + H2O(aq)
- fill half of a test tube, add NaOH and warm gently
- the gas produced makes damn litmus paper turn red
- metal ions
- negative ions
- carbonate ions, (CO3)2-
- react with acids to give bubbles of gas
- this gas produced turns limewater milky
- (CO3)2-(aq) + 2H+(aq) --> H2O(aq) + CO2(g)
- half fill a test tube with sample, add strong acid,
- collect bubbles and pass it through limewater
- if gas turns cloudy, (CO3)2- is present
- collect bubbles and pass it through limewater
- react with acids to give bubbles of gas
- sulfate ions, (SO4)2-
- react with barium ions to form BaSO4 (insoluble)
- Ba2+(aq) + (SO4)2-(aq) -> BaSO4(aq)
- half fill a test tube with the sample, add dilute hydrochloric acid and barium chloride
- white precipitate if (SO4)2- is present
- react with barium ions to form BaSO4 (insoluble)
- halide ions
- dissolve the halide in water if not already aqueous, add some dilute nitric acid and aqueous silver nitrate
- coloured precipitate will form, if hard to distinguish add dilute NH3 then concentrated NH3, note the solubility
- Cl-
- with AgNO3(aq) = white precipitate
- solubility of precipitate = soluble in dilute NH3
- Ag+(aq) + Cl-(aq) --> AgCl(s)
- Br-
- with AgNO3(aq) = cream precipitate
- solubility of precipitate = soluble in concentrated NH3(aq) only
- Ag+(aq) + Br-(aq) --> AgBr(s)
- I-
- Ag+(aq) + I-(aq) --> AgI(s)
- with AgNO3(aq) = yellow precipitate
- solubility of precipitate = insoluble in both dilute and concentrated NH3(aq)
- dissolve the halide in water if not already aqueous, add some dilute nitric acid and aqueous silver nitrate
- carbonate ions, (CO3)2-
- positive ions
Comments
No comments have yet been made