1. Stoichiometry

2. S t o i c h i o m e t r y
A q u a n t i t a t i v e s t u d y o f c h e m i c a l c h a n g e s

3. M a s s - M a s s P r o b l e m s
G i v e n a c e r t a i n a m o u n t o f r e a c t a n t , h o w m u c h p r o d u c t c a n b e f o r m e d ?

4. M a s s - M a s s P r o b l e m s T h e m o l e r a t i o f r o m
t h e c o e f f i c i e n t s i n
a b a l a n c e d e q u a t i o n
i s u s e d t o c h a n g e
f r o m o n e s u b s t a n c e
t o a n o t h e r .

5. M o l e F r a c t i o n
FeS + 2HCl H2S + FeCl2
1 mole FeS = 1 mole H2S

6. M o l e F r a c t i o n
FeS + 2HCl H2S + FeCl2
2 mole HCl = 1 mole H2S

7. Mass-Mass Steps:
1. Write the balanced
equation.

8. Mass-Mass Steps:
2. Put given mass on
a factor-label form.

9. 3. Convert mass of reactant to moles of reactant.
Mass-Mass Steps:
3. Convert mass of reactant to moles
of reactant.

10. Mass-Mass Steps:
4. Convert moles of
reactant to moles
of product.

11. Mass-Mass Steps:
5. Convert moles of
product to grams
of product.

12. Mass-Mass Steps:
6. Pick up the calculator
and do the math.

13. M a s s - M a s s p r o b l e m s u s u a l l y l o o k l i k e t h i s :

14. t h e a i r w i l l c o m b i n e w i t h b o t h t h e i r o n
I f i r o n p y r i t e , F e S 2 , i s n o t r e m o v e d f r o m c o a l , o x y g e n f r o m
t h e a i r w i l l c o m b i n e w i t h b o t h t h e i r o n
a n d t h e s u l f u r a s
c o a l b u r n s.

15. W r i t e a b a l a n c e d
e q u a t i o n s h o w i n g
t h e f o r m a t i o n o f
i r o n ( I I I ) o x i d e
a n d s u l f u r d i o x i d e.

16. N o w t h e m a s s - m a s s p a r t :
I f a f u r n a c e b u r n s a n a m o u n t o f c o a l c o n t a i n i n g g o f F e S 2 , h o w m u c h s u l f u r d i o x i d e i s p r o d u c e d ?

17. M a s s - M a s s P r o b l e m s S t e p 1:
W r i t e t h e b a l a n c e d e q u a t i o n f o r t h e r e a c t i o n .

18. F e S O F e 2 O S O 2

19. B a l a n c e t h e e q u a t i o n :
D i a t o m i c m o l e c u l e s
M e t a l s
N o n m e t a l s
O x y g e n
H y d r o g e n
R e c o u n t a l l a t o m s
R e d u c e , i f n e e d e d

20. 4 F e S O F e 2 O S O 2

21. M a s s - M a s s P r o b l e m s S t e p 2:
W r i t e w h a t i s g i v e n .

22. g F e S 2
W r i t e w h a t i s g i v e n

23. M a s s - M a s s P r o b l e m s S t e p 3:
C o n v e r t m a s s o f r e a c t a n t t o m o l e s o f r e a c t a n t .

24. 1 0 0 g F e S 2
1 m o l e F e S 2
1 2 0 g F e S 2
formula mass:
Fe = 1 X 56 = 56
S = 2 X 32 = 64
120
C o n v e r t g r a m s t o m o l e s

25. M a s s - M a s s P r o b l e m s S t e p 4:
U s e c o e f f i c i e n t s o f r e a c t a n t a n d p r o d u c t i n t h e b a l a n c e d e q u a t i o n

26. R e a c t a n t
4 F e S O F e 2 O S O 2
P r o d u c t

27. M a s s - M a s s P r o b l e m s S t e p 4:
C o n v e r t m o l e s o f r e a c t a n t t o m o l e s o f p r o d u c t .

28. 1 m o l e F e S 2 1 0 0 g F e S 2 2 m o l e S O 2 1 m o l e F e S 2
C h a n g e s u b s t a n c e s

29. M a s s - M a s s P r o b l e m s S t e p 5:
C o n v e r t m o l e s o f p r o d u c t t o g r a m s o f p r o d u c t .

30. 1 m o l e F e S 2 1 0 0 g F e S 2 2 m o l e S O 2 6 4 g S O 2
1 m o l e F e S m o l e S O 2
C o n v e r t m o l e s t o g r a m s

31. M a s s - M a s s P r o b l e m s S t e p 6:
U s e c a l c u l a t o r t o d o t h e m a t h .

32. = 1 0 7 g S O 2 100 g FeS2 1 mole FeS2 2 mole SO2 64 g SO2
D o t h e m a t h

33. R e m e m b e r : F a c t o r - l a b e l c a n c e l s u n i t s
100 g FeS2 1 mole FeS2 2 mole SO g SO2
120 g FeS mole FeS2 1 mole SO2
R e m e m b e r :
F a c t o r - l a b e l
c a n c e l s u n i t s

34. P r a c t i c e

35. Problem #1

36. Problem #2

37. Problem #3

38. More P r a c t i c e

39. How much silver is obtained from the decomposition of 100 grams of silver oxide?

40. 2Ag2O --> 4Ag + O2

41. 100g Ag2O 1 mole Ag2O 4 mole Ag 108g Ag 232g 2 mole 1 mole Ag Ag2O Ag2O
Ag - 2 X 108 = 216
O X 16 = 16
232
93g Ag

42. 50g of iron (II) sulfide react with an excess of HCl in a double displacement reaction. How many grams of hydrogen sulfide are produced?

43. FeS + 2HCl --> H2S + FeCl2 50g FeS 1 mole FeS 1 mole H2S 34g H2S 88g FeS 1 mole FeS 1 mole FeS

44. How much ammonium hydroxide is produced when 25g of ammonium phosphate react with an excess of barium hydroxide in a double displacement reaction?

45. 2(NH4)3PO4 + 3Ba(OH)2 --> 6NH4OH + Ba3(PO4)2 25g mole mole g (NH4)3PO4 (NH4)3PO4 NH4OH NH4OH g mole mole (NH4)3PO4 (NH4)3PO4 NH4OH
18g NH4OH

46. Calcium and aluminum chloride combine in a single displacement reaction. Assuming a sufficient amount of calcium is used, how much aluminum is produced from 10g of aluminum chloride?

47. 3Ca + 2AlCl3 --> 2Al + 3CaCl2 10g AlCl3 1 mole AlCl3 2 mole Al g Al g AlCl mole AlCl3 1 mole Al
2g Al

48. Limiting Reactant

49. The reactant that is
completely consumed
in a reaction

50. the reactant that remains after the reaction stops
Excess reactant:
the reactant that remains
after the reaction stops

51. The amount of product
formed depends on the
limiting reactant

52. Steps used in
solving a
limiting reactant
problem

53. 1.
Write a balanced
equation

54. 2.
Convert BOTH
reactant quantities
to moles

55. 3.
Determine moles
of product formed
by each reactant

56. 4.
The one producing the
LEAST amount is the
limiting reactant

57. Finish the calculation using the limiting reactant5.
Finish the calculation
using the limiting reactant

58. Sample limiting reactant problem
What mass of water can
be produced by 4g of H2
reacting with 16g of O2?

59. Write a balanced equation
Sample limiting reactant problem 1.
Write a balanced equation
for the reaction.

60. 2 H2 + O H2O 2.
Convert both reactant
quantities to moles.

62. Using the mole ratio from the equation, determine the 3.
Using the mole ratio from
the equation, determine the
moles of water that could be
formed by each reactant.

64. 4. Oxygen produces the least amount of water.
16 grams of O2 cannot produce as
much water as 4 grams of H2.
In other words, 16 grams of O2 will
be used up in the reaction before
4 grams of H2.

65. Oxygen is the
"limiting" reactant.
Use oxygen to finish
the calculation
of product amount.

66. Complete the problem by5.
Complete the problem by
converting moles of H2O
to mass of H2O.

68. Limiting reactant practice problem:
75 grams of calcium
oxide react with 130 grams
of hydrochloric acid to
produce a salt and water.
What is the limiting reactant?

69. Limiting reactant practice problem:
CaO + HCl Salt + H2O

70. Limiting reactant practice problem:
CaO + HCl CaCl2 + H2O
Balance the equation

71. Limiting reactant practice problem:
CaO + 2HCl CaCl2 + H2O
Convert both reactants
to moles

72. Convert both reactants to moles of product
75 g CaO 1 mole CaO
56 g CaO
Ca - 1 X 40 = 40
O - 1 X 16 = 16 56
130 g HCl 1 mole HCl
H - 1 X 1 = 1
Cl - 1 X 35 = 35
36 g HCl 36
Convert both reactants
to moles of product

73. Whichever produces the LEAST amount of product is the
75 g CaO 1 mole CaO 1 mole CaCl2
56 g CaO mole CaO
130 g HCl 1 mole HCl 1 mole CaCl2
36 g HCl mole HCl
Whichever produces the LEAST
amount of product is the
limiting reactant.

74. CaO produces 1.3 mole CaCl2 HCl produces 1.8 mole CaCl2
75 g CaO 1 mole CaO 1 mole CaCl2
56 g CaO mole CaO
130 g HCl 1 mole HCl 1 mole CaCl2
36 g HCl mole HCl
CaO produces 1.3 mole CaCl2
HCl produces 1.8 mole CaCl2

75. CaO is the limiting reactant.
75 g CaO 1 mole CaO 1 mole CaCl2
56 g CaO mole CaO
130 g HCl 1 mole HCl 1 mole CaCl2
36 g HCl mole HCl
CaO produces 1.3 mole CaCl2
CaO is the limiting reactant.

76. Homework Problem: How much aluminum oxide is produced when
46.5 g of Al react with
165.37g of MnO?

77. Homework Problem
2 Al + 3 MnO Mn + Al2O3

78. Homework Problem 46.5g Al 1 mole Al 1 mole Al2O3 27g Al 2 moles Al
0.86
46.5g Al 1 mole Al 1 mole Al2O3
27g Al moles Al
Al - 1 X 27 = 27
0.78
165.37g MnO 1 mole MnO 1 mole Al2O3
Mn - 1 X 55 = 55
O - 1 X 16 = 16
71g MnO mole MnO 71

79. Homework Problem 165.37g MnO 1 mole MnO 1 mole Al2O3 102g Al2O3

80. 5 grams of copper metal react with a solution containing #1
5 grams of copper metal react
with a solution containing
20 grams of silver nitrate to
produce copper (II) nitrate
and silver.
A. What is the limiting reactant?
B. How many grams of Ag are produced?

81. 1A. Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag 5g Cu 1 mole Cu 2 mole Ag
0.15
64g Cu mole Cu
0.12
20g AgNO3 1 mole AgNO3 2 mole Ag
170 g AgNO mole AgNO3
silver nitrate is the limiting reactant

82. 1B.
Cu AgNO Cu(NO3) Ag
20g AgNO3 1 mole AgNO3 2 mole Ag g Ag
170 g AgNO mole AgNO3 1 mole Ag
12.7g Ag

83. #2 A solution containing 20 g of sodium
sulfite reacts with 7 ml of phosphoric
acid. The concentration of the acid
solution is such that there are 1.83 g
of H3PO4 per ml of solution.
A. How many g of water are produced?
B. How many moles of Na3PO4 are produced?
C. How many g of SO2 are produced?

84. 3Na2SO3 + 2H3PO Na3PO4 + 3SO2 + 3H2O
20g Na2SO3 1 mole Na2O3 3 mole H2O
0.159
126g Na2SO3 3 mole Na2SO3
12.8g H3PO4 1 mole H3PO4 3 mole H2O
0.196
98g H3PO mole H3PO4
1.83 g ml
= 12.8 g
1 ml

85. 2A.
3Na2SO3 + 2H3PO Na3PO4 + 3SO2 + 3H2O
20g Na2SO3 1 mole Na2O3 3 mole H2O g H2O
126g Na2SO3 3 mole Na2SO3 1 mole
H2O
2.9 g H2O Produced

86. 2B. 3Na2SO3 + 2H3PO4 2Na3PO4 + 3SO2 + 3H2O 17.4 g Na3PO4 Produced
20g Na2SO3 1 mole Na2O3 2 mole Na3PO g Na3PO4
126g Na2SO3 3 mole Na2SO mole Na3PO4
17.4 g Na3PO4 Produced

87. 2C. 3Na2SO3 + 2H3PO4 2Na3PO4 + 3SO2 + 3H2O 10.2 g SO2 Produced
20g Na2SO3 1 mole Na2O3 3 mole SO g SO2
126g Na2SO3 3 mole Na2SO mole SO2
10.2 g SO2 Produced

88. Thirteenth Lab
Copper and Silver Metals

89. END
Stoichiometry