1. Chemical Reactions

2. Formation of Solid Also called precipitate
K2CrO4(aq)+ Ba(NO3)2(aq)-->forms a yellow solid substance
How to identify the solid that forms in a precipitation reaction?
know what happens when an ionic compounds dissolve in water
Ba(NO3) > Ba NO3-
K2CrO > K CrO42-
substances that dissolves in water and produces separated ions are called strong electrolytes
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3. 2K+(aq) + CrO42-(aq) + Ba2+ + 2NO3- How to decide what products form?
K2CrO Ba(NO3)2
2K+(aq) + CrO42-(aq) + Ba NO3-
How to decide what products form?
Recall that a solid compound must have a zero net charge.
The products must contain both anion and cation
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4. Example K2CrO4 Ba(NO3)2 2K+(aq) + CrO42-(aq) + Ba2+ + 2NO3
K+ and Ba+ could not combine
CrO42- and NO3- could not combine
 It should be a combination of positive and negative. Therefore;
K2CrO4 + Ba(NO3)2 ---> BaCrO4 + 2KNO3
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5. Using Solubility Rules
Soluble – dissolves in water
Insoluble / slightly soluble
dissolves tiny amounts that is undetectable to the naked eye
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6. Soluble compounds NO3- salts Na+,K+, NH4+ salts
Cl-, Br-, I- salts except: Ag+, Hg22+ & Pb2+
SO42- salts except for Ba2+, Pb2+, Ca2+

7. Which is the solid substance?
K2CrO4 + Ba(NO3)2 ---> BaCrO4 + KNO3

8. Examples:
When silver nitrate is added to an aqueous solution of potassium chloride, a white solid forms. Identify the white solid and write the balanced equation for the reaction that occurs
AgNO3(aq) + KCl(aq)---> white solid
[Ag+ , NO3- ] + [K+ , Cl-] ----> products
AgNO3 + KCl ----> AgCl KNO3
white solid

9. Focus Question
2. Use the solubility rules in Table 8.1 to predict which of the following is soluble in water
Potassium nitrate
Zinc hydroxide
Calcium carbonate 
Ammonium chloride 
Ans. S,I,I,S ( Note : S- soluble I- Insoluble)

10. Practice problems
When an aqueous solution of barium nitrate is added to an aqueous solution of sodium sulfate, a white solid forms. Identify the white solid and write the balanced equation for the reaction that occurs

11. Answer
Ba(NO3)2 + Na2SO4  BaSO NaNO3
( S) (aq)

12. Types of Chemical Reaction
Synthesis/Combination
Decomposition
Single Replacement
Double Displacement

13. Combination(Synthesis)
2 or more substances combine to form a more complex substance
A + B ----> AB
Ex:
2Ca + O2  2CaO
2SO2 + O2  2SO3

14. Decomposition One substance breaks down to form 2 or more substances
AB -----> A + B
Ex:
HgO > Hg + O2
CaCO3 ----> CaO + CO2
NaHCO3---> Na2CO3 + H2O + CO2

15. Single Replacement A + BC ---> AC + B
One element reacts by replacing another element in a compound
Ex:
Fe + CuSO4 ---> FeSO4 + Cu
Mg + H2SO4 ---> MgSO4 + H2

16. Double Displacement Sometimes called ionic reaction
Characterized by the exchange of ions
AB + CD  AD CB Ex
KCl + Pb(NO3)2  PbCl2 + 2KNO3
K2CrO4 + Ba(NO3)2 ---> BaCrO4(s) + KNO3(l)