Precipitation in Double Displacement Reactions

PIERRE COMASCRISTINA RÍOS

Introduction Double Displacement Reactions

A double displacement reaction involves the reaction of two compounds to form two new compounds. In effect, the compounds change partners with each other.

Purpose

• The purposes of this experiment are:1. To observe precipitation reactions by

mixing aqueous solutions of cations and anions.

2. To write and balance complete chemical equations for precipitation reactions

Purpose

Materials

• The materials needed are the following:

• Pb(NO3)2 CaCl2 • KI NaCl • NaOH FeCl3 • Na2CO3 CuSO4 • AgNO3 Test tubes• KNO3 Test tube racks

• Put 21 clean test tubes in a test tube rack.• Add 6 drops of the solutions indicated which are: KI,

NaCl, NaOH, FeCl3, KNO3, Na2CO3, CuSO4 to 7 clean test tubes . • Add 6 drops of AgNO3 solution to each test tube.• Observe and record information and colour of any precipitate

formed .• Do the same with Pb(NO3)2 and with CaCl2. • Clean the test tubes and dispose of the waste in the waste

container.• And finally write correct equations for all of the reactions

where a precipitate was formed.

Procedure of these reactions

Reactions with AgNo3 • When we add a small quantity of

Potassium Iodide to Silver Nitrate two compounds are produced Potassium Nitrate and a precipitate of Silver Iodide.

• AgNO3 + KI → KNO3 + AgI↓

• The precipitate has a yellow colour.

AgNO3 and NaCl• When we add a small quantity of Sodium

Chloride solution to Silver Nitrate solution it produces Sodium Nitrate and a precipitate of Silver Chloride.

• AgNO3 + NaCl → NaNO3 + AgCl↓

The precipitate has a white

colour.

AgNO3 and CuSO4

• Copper nitrate and Silver Sulphate are formed when Silver Nitrate and Copper Sulphate react with each other.

The precipitate is Silver Sulphate.

• AgNO3 + CuSO4 → Cu(NO3)2 + Ag2SO4

• The colour of the precipitate is a light blue.

AgNO3 and Na2CO3

• Silver Nitrate and Sodium Carbonate react to form Sodium Nitrate and Silver Carbonate. The precipitate is Silver Carbonate.

• AgNO3 + Na2CO3 → Na2CO3 + Ag2CO3↓

• The precipitate’s colour is light green. .

AgNO3 and FeCl3

• Iron Nitrate and Silver Chloride are produced when Silver Nitrate reacts with Iron(III) Chloride.

• AgNO3 + FeCl3 → Fe(NO39 + AgCl3↓

• The precipitate´s colour is light yellow.

Reactions with Lead (II) Nitrate

• Potassium nitrate and Lead Iodide are formed when Lead (II) Nitrate reacts with Potassium Iodide .

• The precipitate is Lead Iodide.• Pb(NO3)2 + 2KI → 2KNO3 + PbI2

• The precipitate´s colour is yellow.

Pb(NO3)2 and NaCl

• When Lead (II) Nitrate reacts with Sodium Chloride it producesSodium Nitrate and Lead (II) chloride.

• Pb(NO3) + 2NaCl →2NaNO3 + PbCl2

• The precipitate has a white colour.

Pb(NO3)2 and KNO3• When Lead (II) Nitrate and Potassium Nitrate react with each other they produce equal products as reactantsbecause, Potassium takes the place of Lead and Lead takes the place of Potassium.

• Pb(NO3)2 + KNO3 → KNO3 + PbNO3

• The precipitate is a

transparent white.

Pb(NO3)2 and Na2CO3

• When Lead (II) Nitrate and Sodium Carbonate react they produce Sodium Nitrate and Lead Carbonate as a precipitate.

• Pb(NO3)2 + Na2CO3 → Na2NO3 + PbCO3

• The precipitate has got a white colour.

Pb(NO3)2 and NaOH• Sodium Nitrate and Lead (II) Hydroxide

are formed when Lead (II) Nitrate and Sodium Hydroxide react with each other.

• Pb(NO3)2 + 2NaOH → 2NaNO3 + Pb(OH)2

• The precipitate has got a white colour.

• In all the reactions Silver was a precipitate because Silver is a solid and does not mix in solutions and is left at the bottom of the test tube.

• The two cations which form precipitates are Iodine and Chloride.

Conclusion

Remember: It is prohibited to drink any of the products used in this experiment.

Thanks for your attention