Reactions & Colours

Question 1

Group 2 metal + water (& example)

Answer 1

Metal + Water –> Metal hydroxide + hydrogen
Mg + 2H₂O –> Mg(OH)₂ + H₂

Question 2

CaO + H₂O –>

Answer 2

CaO + H₂O –> Ca²⁺ + 2OH⁻

Question 3

How to increase ph (neutralize) soil?
+ reaction

Answer 3

By using Calcium hydroxide
Ca(OH)₂ + 2H⁺ –> Ca²⁺ + 2H₂O

Question 4

How to treat indigestion?
+ reaction

Answer 4

Antacids such as Mg(OH)₂
Mg(OH)₂ + 2HCl –> MgCl₂ + 2H₂O

Question 5

Halogens states at RTP

Answer 5

Fluorine: gas
Chlorine: gas
Bromine: liquid
Iodine: solid

Question 6

Halogen-halide displacement reaction colours

Answer 6

Bromine: Orange
Iodine: Violet

Question 7

Chlorine + water?

Answer 7

Cl₂ + 2H₂O –> HClO + HCl
(disproportionation)

Question 8

Test for halide ions

Answer 8

Ag⁺ + X⁻ –> AgX

Question 9

Carbonate test

Answer 9

Carbonates react with acids to form CO₂, bubbling will indicate gas

Question 10

Bubble through limewater

Answer 10

Bubbling CO₂ through limewater will turn it cloudy

Question 11

Sulfate test

Answer 11

Add Ba²⁺ ions to solution, if it forms precipitate it has formed BaSO₄, so it’s sulfate

Question 12

Halide test method

Answer 12

1) Add AgNO₃ to halide solution
2) Form colored precipitate
3) Add ammonia to test solubility

Question 13

Colours + Solubility of AgX

Answer 13

Chlorine: white, soluble in dilute NH₃
Bromine: cream, soluble in conc NH₃
Iodine: yellow, insoluble

Question 14

Order of test

Answer 14

1) carbonates CO₃²⁻
2) sulfates SO₄²⁻
3) halides Cl⁻, Br⁻, I⁻

Question 15

Tests for ammonium ions
method + reaction

Answer 15

1) Add NaOH to solution
2) Ammonia gas will be produced
3) Test with ph
NH₄⁺ + OH⁻ –> NH₃ + H₂O