Chemical equations (Test for anions)

Question 1

The law of conservation of mass

Answer 1

states that the total mass of the products of a chemical reaction is the same as the total mass of the reactants

Question 2

anion

Answer 2

a negative ion

Question 3

Chloride test

Answer 3

1. Add a few drops of AgNO3 solution to a solution of the solid.
2. A white precipitate is formed which is soluble in dilute ammonia solution -> chloride
3. Ag+ + Cl- -> AgCl

Question 4

Sulfate or Sulfite

Answer 4

1. Add BaCl2 solution to a solution of the solid.
2. A white precipitate is formed.
3. Ba2+ + SO4 2- -> BaSO4

Test to distinguish:
1. Add dilute HCl
2. If precipitate remains -> sulfate / If precipitate dissolves -> sulfite
3. BaSO4 + HCl -> no reaction / SO3 2- + 2H+ -> SO2 + H2O

Question 5

Carbonate or Hydrogen - carbonate

Answer 5

1. Add dilute HCl to the solid.
2. Fizzing. A gas is given off that turns limewater milky.
3. CO3 2- + 2H+ -> CO2 + H2O/ HCO3- + H+ -> CO2 + H2O / Ca(OH)2 + CO2 -> CaCO3 + H2O

Test to distinguish:
1. Add MgSO4 solution to a fresh solution of the solid.
2. White precipitate forms -> carbonate/ No precipitate forms -> hydrogencarbonate. Boiling gives a precipitate.
3. Mg2+ + CO3 2- -> MgCO3 / Mg2+ + 2HCO3- -> Mg(HCO3)2 / Mg(HCO3)2 -> MgCO3 + CO2 + H2O

Question 6

Nitrate

Answer 6

1. Brown ring test. To a solution of the solid add a freshly prepared FeSO4 solution. Add concentrated sulfuric acid.
2. A brown ring is formed at the junction of the two liquids -> nitrate.
3. Brown ring is due to presence of nitrate ion.

Question 7

Phosphate

Answer 7

1. Ammonium molybdate is added to a solution of the solid. Concentrated nitric acid is added. Solution is warmed.
2. Yellow precipitate is formed -> phosphate.
3. Phosphate ions are present.