1. Chapter 10
Chemical Reactions

2. Section 10.1  Reactions & Equations
Chemical reaction—process by which the atoms of 1 or more substances are rearranged to form different substances
Evidence of chemical reactions: (fig 10.1)
Temperature change—release energy in the form of heat & light
Color change
Odor is detectable
Gas bubbles
Appearance of a solid (precipitate)

3. Section 10.1  Reactions & Equations
Reactants—starting substances
Products—substances formed during reaction
An arrow () separates products from reactants. You would read the arrow as “react to produce” or “yield.”

4. Section 10.1  Reactions & Equations
Physical states of matter are shown in parentheses.
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous; water solution

5. Skeleton Equation—use chemical formulas rather than words
Word Equation
Iron(s) + chlorine(g)  iron(III) chloride(s)
Skeleton Equation—use chemical formulas rather than words
Fe(s) + Cl2(g)  FeCl3(s)

6. Work practice problems 1-3.
Ex. Solid carbon & solid sulfur(S8) react to form solid carbon disulfide.
Work practice problems 1-3.

7. Practice 1. hydrogen(g) + bromine(g)  hydrobromic acid (aq)
2. carbon monoxide(g) + oxygen(g)  carbon dioxide(g)
3. potassium chlorate(s)  potassium chloride(s) + oxygen(g)

8. Word & skeleton equations lack important information
Word & skeleton equations lack important information. A true chemical equation must show that matter is conserved.

9. Balancing Chemical Equations
Use coefficients—whole # written in front of a formula
Do NOT use 1 as a coefficient in balancing.
The coefficient represents the lowest whole number ratio.
write the skeleton equation.
count the atoms of reactants & products one at a time. (count individual elements in polyatomic ions)
change the coefficient to make the number of atoms of each element equal on both sides of the arrow
**NEVER BALANCE BY CHANGING THE SUBSCRIPTS**
**SAVE OXYGEN & HYDROGEN FOR LAST**

10. Balancing equations
Example:
N2(g) + H2(g)  NH3(g)

11. Practice: Balancing equations
H2(g) + Br2(g)  HBr(g)
CO(g) + O2(g)  CO2(g)
KClO3(s)  KCl(s) + O2(g)
Carbon & sulfur react to form carbon disulfide.

12. ** Balance…

13. 10.2 Classifying Chemical Reactions
1. SYNTHESIS reaction- two or more substances react to form a single product.
A + B  AB
Na + Cl2  __________

15. Example: Synthesis Rxn
Mg + N2 
Mg+2 N-3
 Mg3N2

16. Practice: Synthesis Rxn
__________  CaO
Iron (III) + Oxygen  __(formula)____________

17. 10.2 Classifying Chemical Reactions
2. Combustion reaction- O2 combines with a substance often forming CO2 &/or H2O. (Similar to synthesis)
H2 + O2  H2O
___ + O2  CO2

19. Example: Combustion Rxn
CH4(g) + O2(g)  CO2(g) + H2O(g)

20. Practice: Write a balanced equation & determine type of reaction
The solids aluminum and sulfur(S8) react to produce solid aluminum sulfide.
The gases nitrogen dioxide and oxygen react to produce dinitrogen pentoxide gas.
Ethane gas (C2H6) burns in air to produce carbon dioxide gas and water vapor.

21. 10.2 Classifying Chemical Reactions
3. Decomposition reaction- a single compound breaks into 2 or more new compounds.
AB  A + B
Na3N (s)  __ (s) + __ (g)

23. Decomposition of sugar

24. Example: Decomposition Rxn
___________  Hg (l) + O2 (g)
assume it is mercury (II)

25. Practice: Decomposition Rxn
Al2O3(s) ________+_______
Aqueous nickel(II) hydroxide decomposes to produce nickel(II) oxide & water.
Cu2S  ___________

26. Classify the reaction Na + O2  Na2O CaO  Ca + O2
Synthesis
CaO  Ca + O2
Decomposition
CH4 + O2  H2O + CO2
Combustion
KClO3  KCl + O2
O2 + C5H12  CO2 + H2O
Al + F2  AlF3

27. Classify the reaction C6H14 + O2  Mg + N2  H2O2  Ag + S  Zn + O2 

28. 4. Single Replacement reaction- an atom replace the atom in a compound.
A + BX  AX + B
Cu(II) (s) + 2AgNO3 (aq) 
 ________________

30. Activity Series:
 over there

31. Cu(II) (s) + 2AgNO3 (aq) 
 ________________

33. Copper plating

34. Example: Single replacement
Fe(II) (s) + CuSO4(aq) 
(Fe Cu SO4-2)
 FeSO4(aq) + Cu

35. Practice 2-6 2. Ag(s) + AlPO4(aq)  NR (no reaction)
3. Mg(s) + AlCl3(aq) 
MgCl2(aq) + Al(s)
4. K(s) + ZnCl2(aq) 
KCl(aq) + Zn(s)
5. Br2(l) + MgCl2(aq)  NR
*6. F2(g) + CaCl2(aq)
CaF2(aq) + Cl2(g)

36. 5. Double-replacement reaction- Two compounds react to form 2 new compounds.
In this reaction water, a gas or a solid can be formed.
AX + BY  AY + BX

37. Double replacement rxn

38. Example: Double-replacement Rxn
Ca(OH)2(aq) + 2HCl(aq) 
Ca+2 + OH-1 + H+1 + Cl-1
 CaCl2(aq) + 2H2O(l)

39. Practice: Double Replacement Rxn
NaOH(aq) + CuCl2(aq) 
Na+1 + OH-1 + Cu+2 + Cl-1
 NaCl(aq) + Cu(OH)2(s)
KCN(aq) + HBr(aq) 
K+1 + CN-1 + H+1 + Br-1
 KBr + HCN

40. Practice:Give the balanced skeletal for the following.
1. Aqueous barium chloride and aqueous potassium carbonate react to produce solid barium carbonate and aqueous potassium chloride.
BaCl2(aq) + K2CO3(aq)  BaCO3(s) + 2KCl(aq)
2. Aqueous lithium iodide and aqueous silver(I) nitrate react to produce solid silver(I) iodide and aqueous lithium nitrate.
LiI(aq) + AgNO3(aq)  AgI (s) + LiNO3(aq)

41. Classify each rxn CH4 + O2  H2O + CO2 KClO3(s)  KCl(s) + O2(g)
Combustion
KClO3(s)  KCl(s) + O2(g)
decomposition
ZnCl2(aq) + K(s)  KCl(aq) + Zn(s)
Single-replacement
BaCl2+ K2CO3 BaCO3+ 2KCl
Double-replacement
CaCl2(aq) + F2(g)  CaF2(aq) + Cl2(g)

42. Classify & Predict CuO  Mg + O2  Ca + N2  C3H8 + O2  HCl + BaSO4 
Fe + CuCl2 
Cu3N + Zn 
**Classify each equation on “Balancing eq” handout