Testing for Anions

Question 1

describe the test for Chloride (Cl-)

Answer 1

add a few drops of silver nitrate to the solution
a white ppt is formed which is soluble in ammonia
the whit ppt is silver chloride
no ppt= no chloride

Question 2

describe the test to test for sulphate and sulphite

Answer 2

add barium chloride to both and a white ppt is formed
to test for difference between sulphite and sulphate add dilute HCl
sulphate: ppt remains
sulphite: ppt dissolves

Question 3

describe the test to test for carbonate or hydrogen carbonate

Answer 3

add dilute HCl to the solid, fizzing occurs
to test for the difference, add magnesium sulphate to a solution of the solid
carbonate: white ppt forms
hydrogencarbonate: no ppt

Question 4

test for the presence of nitrate

Answer 4

add fresh iron (II) sulphate to the solution and add concentrated sulphuric acid carefully down the side of the slanted test tube
a brown ring will form between the 2 liquid layers if nitrate is present

Question 5

test for the presence of phosphate

Answer 5

ammonium molybdate is added to the solution. concentrated nitric acid is added and the solution is heated gently. a yellow ppt is formed
yellow ppt= ammonium phosphomolybdate

Question 6

formula for chloride

Answer 6

Ag+ + CL- —–> AgCl (downward facing arrow)

Question 7

formula for step 1 of sulphate

Answer 7

Ba+2 + SO4-2——>BaSO4 (downward facing arrow)

Question 8

formula for step 1 of sulpite

Answer 8

Ba+2 + SO3-2——>BaSO3

Question 9

formula for step 2 of sulphate and sulphite

Answer 9

BaSO4 + HCl ——–> no rxn (sulphate)
BaSO3 + HCl———>SO2 + H2O

Question 10

formula for carbonate

Answer 10

CO3-2 + 2H+——-> CO2 + H2O

Mg+2 + CO3-2 ——-> MgCO3(downward arrow)

Question 11

formula for hydrogencarbonate

Answer 11

HCO3- + H+——-> CO2 + H2O
Mg+2 + 2HCO3—–> Mg(HCO3)2