1. Making insoluble salts
Lesson 5

2. Learning intentions Analyse graphs to discuss solubility
Carry out practical procedures safely to obtain insoluble salts

6. Solubility of salts – the rules
Soluble Salts
Insoluble Salts
All nitrates
Most sulfates
Most chlorides, bromides and iodides
Sodium carbonate, potassium carbonate
Sodium hydroxide, potassium hydroxide
None
Lead sulfate, barium sulfate
Silver chloride, silver bromide, silver iodide, lead chloride, lead bromide, lead iodide
Most other carbonates
Most other hydroxides

7. Precipitation reactions – making an insoluble salt
REACTION Silver Nitrate with Sodium Chloride
Measure 10 cm3 of Sodium Chloride solution and pour into test tube 1
Rinse out the measuring cylinder
Add drops of Silver Nitrate solution to the test tube.
Is there a precipitate? Yes / No Colour of precipitate _____________________
Write the symbol equation for this reaction:
__________________ + ___________________  __________________ + ___________________

8. Measure 10cm3 of Iron Sulfate solution and pour into test tube 2
REACTION Iron Sulfate with Sodium Hydroxide
Measure 10cm3 of Iron Sulfate solution and pour into test tube 2
Rinse out the measuring cylinder
Add drops of Sodium Hydroxide solution to the test tube.
Is there a precipitate? Yes / No Colour of precipitate _____________________
Write the symbol equation for this reaction:
__________________ + ___________________  __________________ + ___________________

9. Measure 10 cm3 of Barium Chloride solution and pour into test tube 3
REACTION Barium chloride with Hydrochloric Acid
Measure 10 cm3 of Barium Chloride solution and pour into test tube 3
Rinse out the measuring cylinder
Add drops of Hydrochloric Acid solution to the test tube.
Is there a precipitate? Yes / No Colour of precipitate _____________________
Write the symbol equation for this reaction:
__________________ + ___________________  __________________ + ___________________

10. Measure 10 cm3 of Copper Sulfate solution and pour into test tube 4
REACTION Copper Sulfate with Sodium Hydroxide
Measure 10 cm3 of Copper Sulfate solution and pour into test tube 4
Rinse out the measuring cylinder
Add drops of Sodium Hydroxide solution to the test tube.
Is there a precipitate? Yes / No Colour of precipitate _____________________
Write the symbol equation for this reaction:
__________________ + ___________________  __________________ + ___________________

11. How to collect the insoluble salt
What could you do to separate the precipitate from the solution?
How would you know if your reaction has produced a good yield?

12. How to Prepare an Insoluble Salt (precipitate) by Precipitation
Step 1
Mix the 2 soluble salts together,
so they react together
Step 2
Filter the mixture, to separate the products produced (soluble & insoluble salt produced)
PRODUCT
Insoluble salt
REACTANT
Soluble salt
REACTANT
Soluble salt
PRODUCT
Soluble salt
PRODUCT
Insoluble salt
PRODUCT
Soluble salt
Step 3
Wash the insoluble salt on the filter paper
Step 4
Dry the insoluble salt in a warm oven
You will prepare an insoluble salt by reacting together 20 cm3 of lead nitrate solution and 20 cm3 of potassium iodide solution
Write the symbol equation: __________________ + __________________ __________________ + _________________
What is the name of the precipitate (insoluble salt) produced? __________________________
What colour is this precipitate?___________________________

13. When may new need to carry out precipitation reactions in everyday life?

14. Plenary
Most chlorides, sulfates and nitrates are soluble/insoluble in water.
Most oxides and hydroxides are soluble/insoluble in water.
Soluble salts can be made by reacting acids/alkalis with insoluble bases until they are just neutralised/displaced.
Insoluble salts are made by precipitation/electrolysis.

15. A,B and C are symbol equations for reactions in which salts are formed
CuO(s) + H2SO4 (aq) CuSO4(aq) + H2O(l)
2NaOH(aq) + H2SO4 (aq) Na2SO4(aq) + 2 H2O(l)
Pb(NO3)2(aq) + H2SO4 (aq) PbSO4(s) + 2HNO3(aq)
Which equation refers to formation of a salt by:
An acid/alkali equation
By precipitation
From an insoluble base