halide ions Flashcards
what is the equation for the reaction of NaCl with sulfuric acid?
Cl- + H₂SO₄ = HCl + HSO₄-
what is the equation for the reaction of NaBr with sulfuric acid?
2Br- + H₂SO₄ + 2H+ = Br₂ + SO₂ + 2H₂O
what is the equation for the reaction of NaI with Sulfuric acid?
6I- + H₂SO₄ + 6H+ = 3I₂ + S + 4H₂O
8I- + H₂SO₄ + 8H+ = 4I₂ + H₂S + 4H₂O
what observations are there for NaCl+H₂SO₄
HCl - steamy white fumes, turns litmas paper red
what observations are there for NaBr+H₂SO₄
Br₂- orange vapour
SO₂- choking gas
what observations are there for NaI+H₂SO₄
S- yellow solid
I- purple vapour
HS- foul smelling gas
give a test for halide ions
react with acidified silver nitrate solution and forms a ppt
Ag+(aq) + X-(aq) = AgX (s)
what colour ppt does AgCl form?
white
what colour ppt does AgI form?
yellow
what colour ppt does AgBr form?
cream
what colour ppt does AgF form?
none as it is soluble
what happens to AgCl when ammonia is added?
dissolves
what happens to AgI when ammonia is added?
insoluble in ammonia so ppt remains
what happens to AgBr when ammonia is added?
dissolves in excess ammonia
why must silver nitrate must be acidified when being used to test for halide ions?
prevents the formation of sodium carbonate which forms as a result of carbon dioxide dissolving in the solution
give a test for ammonium ions
add warm NaOH solution which produces ammonia gas. test with damp red litmas paper which turns blue
NH₄+(aq) + OH-(aq) = NH₃(g) + H₂O(l)
give a test for carbonate ions
Add HCl or H₂SO₄ or HNO₃ and bubble the gas produced through lime water which forms a white ppt due to CO₂ produced
2H+(aq) + CO₃2- (aq) = H₂O(l) + CO₂(g)
give a test for hydroxide ions
add a solution of Mg2+ ions and a white ppt is formed
Mg2+(aq) + 2OH-(aq) = Mg(OH)₂(s)
give a test for sulfate ions
add acidified barium chloride and a white ppt is formed
Ba2+(aq) + SO₄2-(aq) = BaSO₄(s)
explain why barium chloride must be acidified when testing for sulfate ions
prevents the formation of BaSO₃ which forms when carbon dioxide is dissolved in the solution
explain why acidified barium chloride or silver nitrate solution reacts with carbonate ions
both contain acid that reacts with carbonate ions to produce carbon dioxide
give two sources of aqueous sulfate ions
group 1 sulfate salts and sulfuric acid
give the first step to test any unknown inorganic solid
dissolve in water
