Reactions & Tests Flashcards
Group 2 metal + water (& example)
Metal + Water –> Metal hydroxide + hydrogen
Mg + 2H₂O –> Mg(OH)₂ + H₂
CaO + H₂O –>
CaO + H₂O –> Ca(OH)₂
How to increase ph (neutralize) soil?
+ reaction
By using Calcium hydroxide
Ca(OH)₂ + 2H⁺ –> Ca²⁺ + 2H₂O
How to treat indigestion?
+ reaction
Antacids such as Mg(OH)₂
Mg(OH)₂ + 2HCl –> MgCl₂ + 2H₂O
Halogens states at RTP
Fluorine: gas
Chlorine: gas
Bromine: liquid
Iodine: solid
Halogen-halide displacement reaction colours
Bromine: Orange (Br₂ formation, displaced)
Iodine: Violet (I₂ formation, displaced)
Chlorine + water?
Cl₂ + H₂O –> HClO + HCl
(disproportionation)
Test for halide ions
Ag⁺ + X⁻ –> AgX
Carbonate test
Carbonates react with acids to form CO₂, bubbling will indicate gas
Bubble through limewater
Bubbling CO₂ through limewater will turn it cloudy
Sulfate test
Add Ba²⁺ ions to solution (dilute acid), if it forms precipitate it has formed BaSO₄, so it’s sulfate
Halide test method
1) Add AgNO₃ (with dilute HNO₃) to halide solution
2) Form colored precipitate
3) Add ammonia to test solubility
Colours + Solubility of AgX
Chlorine: white, soluble in dilute NH₃
Bromine: cream, soluble in conc NH₃
Iodine: yellow, insoluble
Order of test
1) carbonates CO₃²⁻
2) sulfates SO₄²⁻
3) halides Cl⁻, Br⁻, I⁻
Tests for ammonium ions
method + reaction
1) Add NaOH to solution
2) Ammonia gas will be produced
3) Test with ph
NH₄⁺ + OH⁻ –> NH₃ + H₂O
What colour does NH3 (g) turn litmus paper?
blue -> red
Test for aldehydes
Tollen’s reagent, will form silver mirror
Test for carbonyl group (+colour change)
2,4-DNP
Will form yellow-orange-red ppt
Fehling’s solution
Distinguish between Aldehyde & Ketone
Aldehydes: Oxidized by Fehling’s, from blue to red precipitate)
Ketones: No reaction, cannot be oxidized further
Chlorine + Sodium Hydroxide (+ reaction type)
Cl₂ + 2NaOH –> NaCl + NaClO + H₂O (disproportionation reaction)
