1. Chemical Reactions and Equations
Chapter 8

2. Chemical reactions…. Process by which one or more substances are
described by a

3. 4 Signs of a Chemical Reaction:
Evolution of _________ and ________________
2. Production of ______________
3. Formation of a _____________________(solid produced as a result of a chem rxn in a sol’n)
4. _____________________change

4. Chemical equation (NH4)2Cr2O7(s) ---> N2(g) + Cr2O3(s) + 4H2O(g)
Represents the identities and relative amounts of the reactants and products in a chemical reaction
(NH4)2Cr2O7(s) ---> N2(g) + Cr2O3(s) + 4H2O(g)
Characteristics:
represents the _______________________________
contains correct _________________ for the reactants & products
satisfies the law of ____________________________ (same # and kind of atoms on both sides of the equation)

5. (NH4)2Cr2O7(s)---> N2(g) + Cr2O3(s) + 4H2O(g)
Formula equation: uses symbols/formulas to represent the reactants and products
Reactants
products
coefficient (understood to be “1” if no # appears
symbols (p.246)

6. ammonium dichromate --> nitrogen + chromium(III) oxide + water
Word equation: (previous ex.)
only fulfills ONE characteristic of a chem eq
(____________________________________)
1st step in writing a balanced chemical equation

7. Steps to write a balanced chemical equation:
1. Write the word equation.
2. Convert the word equation into a formula equation.
3. Include symbols, where known.
4. Balance the equation. NEVER CHANGE A SUBCRIPT IN BALANCING EQUATIONS!

8. Cu + H2SO4  CuSO4 + SO2 + H2O Cu H S O
Cu + H2SO4  CuSO4 + SO2 + H2O

9. SiF4 + H2O  H2SiF H2SiO3 Si F H O
SiF H2O  H2SiF H2SiO3

10. Solutions of lead(II) nitrate and sodium hydroxide react to produce a lead(II) hydroxide precipitate and an aqueous solution of sodium nitrate.

11. Solid rubidium oxide reacts with water to produce an aqueous solution of rubidium hydroxide.

12. Lithium reacts with a hydrochloric acid solution to produce an aqueous solution of lithium chloride and hydrogen.

13. In the presence of an electrical current, sodium hydroxide can be produced from the reaction of a sodium chloride solution with water. Hydrogen and chlorine gases are the other products.

14. Aluminum sulfate is produced when aluminum hydroxide reacts with sulfuric acid. Water is the other product.

15. 5 types of chemical reactions:
synthesis (composition)
decomposition
single-replacement (displacement)
double-replacement (displacement)
combustion

16. Synthesis Reactions
2 or more substances combine to form a new compound
2 H O2  2H2O

17. Reactions of metals with oxygen and sulfur
magnesium metal + oxygen 
barium + sulfur (S8) 

18. Some metals can form oxides of varying oxidation #:
iron + oxygen  iron(II) oxide
iron + oxygen  iron(III) oxide

19. Nonmetals can also form oxides
S8(s) + 8O2(g)  8SO2(g)
C(s) + O2(g)  CO2(g)
2C(s) + O2(g)  2CO(g)

20. Reactions of metals with halogens
potassium + iodine 
strontium + bromine 
cobalt + fluorine  [cobalt(III) ion forms]

21. Synthesis reactions with metal oxides
active metals* oxides + water  hydroxides
calcium oxide + water 
*(see p. 266)

22. Synthesis reactions with nonmetal oxides
nonmetal oxides + water  oxyacids
sulfur dioxide + water 

23. Synthesis reaction of metal oxide & nonmetal oxide
calcium oxide + sulfur dioxide 

24. Decomposition
a single cmpd undergoes a rxn that produces 2 or more simpler substances
H2CO3  H2O + CO2

25. Decomposition of…
binary cmpds
metal carbonates
metal hydroxide
metal chlorates
acid

26. Decomposition of binary cmpds
simplest decomposition rxn
decomposition into elements
ELECTROLYSIS: decomp by an electric current
2 H2O(l) electricity--->

27. Decomposition of Metal Carbonates
when heated (∆), produce a metal oxide and carbon dioxide gas
CaCO3(s) -∆

28. Decomposition of Metal Hydroxides
all metals except Gp 1 decomp when heated to produce metal oxides and water
Ca(OH)2(s) -∆ CaO(s) + H2O(g)

29. Decomposition of Metal Chlorates
when heated, decompose to produce a metal chloride and oxygen
KClO3(s) -∆ 2KCl(s) + 3O2(g)

30. Decomposition of Acids
Many acids decompose into nonmetal oxides and water
H2SO4(aq) -∆
H2CO3(aq) 

31. Single Replacement Reaction
one element replaces a similar element in a cmpd
2 Al Fe2O3  Al2O Fe

32. Single Replacement Reaction of…
a metal in a cmpd by another metal
hydrogen in water by a metal
hydrogen in an acid by a metal
replacement of halogens

33. Replacement of a metal in a cmpd by another metal
aluminum + lead(II) nitrate 
(p. 266 Al is more reactive than Pb so a spontaneous reaction will occur)

34. Replacement of H in water by a metal (active)
very active metals (i.e. Gp 1) pulls one H from the water
sodium + water 

35. Replacement of H in water by a metal (less-active)
less- active metals reacts with steam and pulls-off both hydrogens from the water
iron + water 

36. Replacement of H in an acid by a metal
more-active metals reacts with some acidic soln’s
magnesium + hydrochloric acid 

37. Replacement of Halogens
a more reactive halogen will replace a
less-active halogen
the higher up in the Gp 17 family, the MORE reactive the halogen
Reactivity: F>Cl>Br>I
chlorine gas + potassium bromide sol’n 

38. fluorine gas + sodium chloride sol’n 
bromine liquid + potassium chloride sol’n 

39. Double replacement reactions
ions of 2 cmpds exchange places in an aqueous solution to form 2 new cmpds
ZnBr AgNO3  Zn(NO3)2 + 2 AgBr

40. Double displacement reactions…..
formation of a precipitate
formation of a gas
formation of water

41. Formation of a precipitate
one product is insoluble (or just slightly soluble) …see page 427
potassium iodide + lead (II) nitrate 

42. Formation of a gas one product is an insoluble gas and bubbles out
iron(II) sulfide + hydrochloric acid sol’n 

43. Formation of Water one of the products yields the molecular cmpd water
hydrochloric acid + sodium hydroxide 

44. Combustion Reactions
substance reacts with oxygen and releases a large amount of energy (light and heat)
hydrogen + oxygen  water vapor
hydrocarbon + oxygen  carbon dioxide + water

45. Combustion (burning) of propane:
C3H8(g) + O2 

46. Will cobalt react with sodium chloride? Co(s) + NaCl(aq)  ?

47. Activity Series
list of elements organized according to the ease with which the elements undergo certain chemical reactions
are
at the TOP and can replace a metal in a cmpd found below it in single displacement reactions

48. water X
steam
acid
oxygen

49. Will the following react? IF so, write an equation.
Mn + H2O C ?
Cd + O2 
Ag + HCl 

51. Will the following react? Write an equation if it does.
Br2 and HCl 
Cl2 and KI 