This document discusses net ionic equations and solubility curves. It provides examples of writing net ionic equations by identifying spectator ions and writing the net reaction. It also discusses solubility curves and using them to determine the solubility of substances at different temperatures and whether solutions are saturated, unsaturated or supersaturated. Homework includes practice with net ionic equations and using solubility curves to solve problems involving precipitation reactions and limiting reactants.

1. Predicting Solubilities

2. Net Ionic Equations
• In reactions that occur in solution, write the
equation for the reaction in ionic form
▫ Indicate the ionic species that actually exist in
solution.

3. BaCl2(aq) + Na2SO4(aq)  BaSO4(s) + 2NaCl(aq)
• BaSO4 is an insoluble product (i.e. a precipitate)
• An ionic equation is to break apart aqueous
products and reactants
▫ BaCl2(aq)
▫ Na2SO4(aq)
▫ NaCl(aq)

4. BaCl2(aq) + Na2SO4(aq)  BaSO4(s) + 2NaCl(aq)
Ionic Equation:
2Na1+(aq) + SO42-(aq) + Ba2+(aq) + 2Cl1-(aq)  2Na1+(aq)
+ 2Cl1-(aq) + BaSO4(s)
Note: BaSO4(s) cannot be broken down

5. 2Na1+(aq) + SO42-(aq) + Ba2+(aq) + 2Cl1-(aq)  2Na1+(aq)
+ 2Cl1-(aq) + BaSO4(s)
• Sodium and chloride ions are unchanged and are
present on both sides of the equation.
▫ Since they are not undergoing chemical reaction,
they can be referred to as spectator ions.
• If we subtract the spectator ions from each side
of the equation, we then have a net ionic
equation.

6. 2Na1+(aq) + SO42-(aq) + Ba2+(aq) + 2Cl1-(aq)  2Na1+(aq)
+ 2Cl1-(aq) + BaSO4(s)
• The net ionic equation for the above reaction is:
Ba2+(aq) + SO42-(aq) -----> BaSO4(s)

7. • Note: You must pay attention to reactions that
occur.
▫ Use the solubility tables that you copied in the last
unit to determine whether the reaction will occur
▫ Consider if the reactions are single displacement
or double displacement

8. Example
• Write the net ionic reaction. Be sure to include
charges on ions.
K2CrO4(aq) +Ba(NO3)2(aq) → 2KNO3 (aq)+ BaCrO4(s)

9. Learning Check
• Write the net ionic reaction. Be sure to include
charges on ions.
KCl(aq) + AgNO3(aq) → KNO3(aq) + AgCl(s)

10. Learning Check
• Write the net ionic reaction. Be sure to include
charges on ions.
3KOH(aq) + Fe(NO3)3(aq) → 3KNO3 (aq) + Fe(OH)3(s)

11. Solubility Curves

12. • Solubility curves,
like the one shown
here, tell us what
mass of solute will
dissolve in 100g (or
100mL) of water over
a range of
temperatures.
• The solutions are
saturated at the given
temperatures.

13. Example:
• What mass of solute will
dissolve in 100mL of
water at the following
temperatures.
1. KNO3at 70°C
2. NaCl at 100°C
3. NH4Cl at 90°C

14. Example:
• Which of the three
substances is most
soluble in water at
15°C.
1. KNO3at 70°C
2. NaCl at 100°C
3. NH4Cl at 90°C

15. Example:
• State whether the
following solutions are
saturated, unsaturated
or supersaturated
1. 100 g of KNO3at 60°C
2. 30 g of NaCl at 80°C
3. 80g of NH4Cl at 90°C

16. • You'll notice that for most substances, solubility
increases as temperature increases.
• In solutions involving liquids and solids typically
more solute can be dissolved at higher
temperatures.
• There are exceptions to this rule, however, we
will not get into them in this course.

17. Homework
• Solubility Curve Worksheet

18. Concentration of a Solution from the
Mass of the Precipitate
• A student carefully measured 100 mL of a silver
nitrate solution, AgNO3(aq), of unknown
concentration and added a copper coil. When
the reaction was complete, the solution was
filtered to obtain all the silver. The dry
precipitate had a mass of 1.65 g. What was the
molar concentration of the silver nitrate
solution?

20. Limiting Reactants and Precipitates
In water purification, aluminum sulfate,
Al2(SO4)3(aq), reacts with calcium hydroxide,
Ca(OH)2(aq), to form a precipitate of aluminum
hydroxide, Al(OH)3(s).
a) Write a balanced equation.

21. b) Find the mass of aluminum hydroxide that
precipitates when 20.0 mL of 0.0150 mol/L
aluminum sulfate is mixed with 30.0 mL of
0.0185 mol/L aqueous calcium hydroxide.

22. Minimum Volume for a Complete
Reaction
A kidney stone contains primarily calcium
oxalate, CaC2O4(s). A chemist wants to react 60.0
mL of 0.135 mol/L sodium oxalate, Na2C2O4(aq),
with 0.226 mol/L calcium chloride, CaCl2(aq), to
precipitate calcium oxalate.
a) Write a balanced equation.

23. b) What mass of calcium oxalate will be
precipitated?

24. c) What is the minimum volume of calcium
chloride solution required?

25. Homework
• Pg 417 Q 12, 13, 14
• Pg 420 Q 21 , 22