1. Chapter 7 Part II Notes

2. Determining Products of Reactions
To predict the products for any equation, you must first determine
Synthesis –
Decomposition –
Combustion –

3. Reaction Prediction
2 or more reactants and you’re told that there’s only one product =
When writing the products, you must look at the charges of the ions.
Example: Al(s) + Br2(l) 
Example: Ca(s) + N2(g) 

4. Reaction Prediction 1 reactant = decomposition
Remember the “7” diatomic molecules and
Example: CCl4(l) 
Example: Mg3N2(s) 

5. Reaction Prediction hydrocarbon (compound with C & H) + O2 =
Example: CH4(g) + O2(g) 
Example: C3H8O(g) + O2(g) 

6. More Examples
C8H18 + O2 
Ba(NO3)2 
Mg + O2

7. Reaction Prediction Part 2
Single displacement – 1 element & 1 compound react
Double displacement – 2 compounds react
Neutralization – acid and base in the reactants

8. Reaction Prediction 1 element & 1 compound =
In the products, you can’t have
Example: Mg(s) + Zn(NO3)2(aq) 
Example: Cl2(g) + KF(aq) 

9. Reaction Prediction 2 ionic compounds = Example:
AgNO3(aq) + NaCl(aq) 
Fe2(SO4)3(aq)+ Na3PO4 (aq)

10. Reaction Prediction 1 acid (starts with H) & 1 base (ends with OH) =
Water gets rid of all hydrogen and hydroxide ions.
Example: HCl(aq) + KOH(aq) 
Example: Ca(OH)2(aq)+ H2SO4(aq)

11. More Examples

12. Solubility If a substance is an aqueous solution (aq),
If a substance is insoluble,
Insoluble substances form as the result of
If a substance is slightly soluble or partially soluble in water,

14. Figure 7.3: Solubilities of common compounds.

15. Solubility Examples
Ca(NO3)2
CuOH
CaCl2
(NH4)2SO4
Zn3(PO4)2
FeCO3
SrO

16. Precipitation Reactions
in all precipitation reactions,
At least one of the products formed is
KI(aq) + AgNO3(aq)  KNO3(aq) + AgIs K+ I-
Ag+
NO3- Ag I 3

17. Dissociation Occurs in ionic compounds and acids
when ionic compounds dissolve in water the anions and cations are separated from each other; this is called dissociation
we know that ionic compounds dissociate when they dissolve in water because the solution conducts electricity 4

18. Electrical conductivity of aqueous solutions
Electrical conductivity of aqueous solutions. (a) Pure water does not conduct an electric current. (b) When an ionic compound is dissolved in water, current flows and the lamp lights.

19. Figure 7.5: When gaseous HCl is dissolved in water, each molecule dissociates to produce H+ and Cl- ions.

20. Dissociation potassium chloride dissociates in water
KCl(aq) = K+ (aq) + Cl- (aq)
copper(II) sulfate dissociates in water
CuSO4(aq) = Cu+2(aq) + SO42-(aq) K+
Cl- K Cl
Cu+2
SO42- Cu
SO4 5

21. K2SO4(aq) = 2 K+ (aq) + SO42-(aq)
Dissociation
potassium sulfate dissociates in water
K2SO4(aq) = 2 K+ (aq) + SO42-(aq) K+
SO42- K
SO4 6

22. Process for Predicting the Products of a Precipitation Reaction
Determine what ions
Exchange Ions
(+) ion from one reactant with (-) ion from other
Balance Charges of combined ions to
Balance the Equation
count atoms
Determine Solubility
solubility rules
if product is insoluble or slightly soluble, 7

23. Figure 7.1: The precipitation reaction that occurs when yellow potassium chromate, K2CrO4(aq), is mixed with a colorless barium nitrate solution, Ba(NO3)2(aq).

24. Figure 7.4: Precipitation of silver chloride occurs when solutions of silver nitrate and potassium chloride are mixed.

26. Example Problems
Predict the products given each of the following reactants. Also denote which compound forms a precipitate:
Cu(NO3)2(aq) + KOH(aq) 
FeCl3(aq) + Mg3(PO4)2(aq) 
NaBr(aq) + AgNO3(aq) 