1. Chemical Reactions
Chapter 11

2. Reactions
Reactants
Products

3. Chemical Changes Indications of a chemical change Transfer of Energy
Change in temperature
Production of Light
Formation of a gas
Formation of a precipitate (solid)
Change in color

4. Balancing Reactions
Reactions must maintain conservation of mass, charge, and energy
Reactants and Products must have the same number of atoms of each element
2 H2 + O2  2 H2O
Total mass of Reactants must equal the total mass of Products

5. Balancing Reactions
Reactions must maintain conservation of mass, charge, and energy
Reactants must have the same total charge as Products
Cu Fe+3  Cu Fe+2

6. Balancing Reactions To balance a reaction:
Do NOT change chemistry (compounds, subscripts)
Only change coefficients (big numbers in front of chemicals)
Coefficients can only be whole numbers
Must be simplest whole number ratio
2 H2 + O2  2 H2O

7. Balancing Reactions 4 Na + O2  2 Na2O 2 Al + 3 Br2  2 AlBr3
4 Ni O2  2 Ni2O3
2 HNO3 + Ca(OH)2  Ca(NO3) H2O

9. Reaction Types Synthesis Decomposition Single Replacement
Double Replacement

10. Synthesis
Chemical change in which two or more substances react to form a single new substance (1 product)
Also called Combination
A + B  AB
2Mg + O2  2MgO

11. Synthesis Examples 2 Ca + O2  2 CaO 2 Na + F2  2 NaF
4 K + O2  2 K2O
Mg + Cl2  MgCl2

12. Decomposition
Chemical change in which a single compound breaks down into two or more simpler products
1 reactant
AB  A + B
2NaCl  2Na + Cl2

13. Decomposition Examples
2 Fe2O3  4 Fe + 3 O2
2 H2O  2 H2 + O2
2 Na3N  6 Na + N2
2 KI  2 K + I2

15. Single Replacement
Chemical change in which one element replaces a second element in a compound
Metal replaces metal (hydrogen included)
Nonmetal replaces nonmetal
A + BC  AC + B
A + BC  BA + C
Zn + 2HCl  ZnCl2 + H2

16. Single Replacement Examples
Zn + CuSO4  Cu + ZnSO4
4 Al + 3 TiCl4  3 Ti + 4 AlCl3
3 Ag + AuCl3  Au + 3 AgCl
3 Mg + 2 AlPO4  2 Al + Mg3(PO4)2

17. Double Replacement
Chemical change involving an exchange of positive ions between compounds
AB + CD  AD + CB
AgNO3 + NaCl  NaNO3 + AgCl

18. Double Replacement Examples
NaCl + AgNO3  NaNO3 + AgCl
K2S + CdCl2  2 KCl + CdS
K2SO4 + BaCl2  2 KCl + BaSO4
3 NH4OH + AlCl3  3 NH4Cl + Al(OH)3

20. Spontaneous Reactions
A single replacement reaction will only occur if:
The single element in the reactants is more active than the element it replaces in the compound

21. Table J The more active element: Does not want to be alone
Wants to be combined with someone else

22. Spontaneous or not? ZnCO3 + Mg  MgCO3 + Zn PbSO4 + Mn  MnSO4 + Pb
3KNO3 + Al  Al(NO3)3 + 3K
2HCl + Zn  ZnCl2 + H2
2NaBr + I2  2NaI + Br2
YES
YES NO
YES NO

23. Spontaneous Reactions
A double replacement reaction will only occur if:
A precipitate (solid) is produced
A liquid is produced
H2O(l)
A gas is produced

24. Table F

25. Spontaneous or not? NaCl + AgNO3  NaNO3 + AgCl
K2CO3 + MgSO4  K2SO4 + MgCO3
NH4OH + NaNO3  NaOH + NH4NO3
Yes
Yes No