1. HW3

2. 58. What is the density of each of these gases at STP?Ne
NO2

3. 58. What is the density of each of these gases at STP?
C3H8 molar mass = 44 g
Ne molar mass = 20.2
NO2 molar mass = 46 g
Molar volume is 22.4 L

4. 58. What is the density of each of these gases at STP?
C3H8 44g / 22.4L= 1.96 g/L
Ne 20.2g / 22.4L= .90 g/L
NO2 46g / 22.4L= 2.05 g/L

5. 60. Calculate the percent composition of each compound
H2S
(NH4)2C2O4
Mg(OH)2
Na3PO4

6. 60. Calculate the percent composition of each compound
H2S
Molar mass is 34g
Percent composition of an element is mass of that element divided by the molar mass of the compound X 100
% H is 2/34 X 100 = 6%
% S is 32/34 X 100 = 94%

7. 60. Calculate the percent composition of each compound
B. (NH4)2C2O4 Molar mass = 124g %N is 28/124 X 100 = 22.6% %H is 8/124 X 100 = 6.5% % C is 24/124 X 100 = 19.3% % O is 64/124 X 100 = 51.6%

8. 60. Calculate the percent composition of each compound
C. Mg(OH)2 Molar mass = 58.3g %Mg is 24/58 X 100 = 41% %O is 32/58 X 100 = 55% %H is 2/58 X 100 =4%

9. 60. Calculate the percent composition of each compound
D. Na3PO4 Molar mass = 164 % Na is 69/164 X 100 = 42% % P is 31/164 X 100 = 19% % O is 64/164 X 100 = 39%

10. 62. Which of the following compounds has the highest iron content?
FeCL2
Fe(C2H3O2)3
Fe(OH)2
FeO

11. 62. Which of the following compounds has the highest iron content?
FeCL2
Fe(C2H3O2)3
Fe(OH)2
FeO
What are the molar masses?
What are the percent compositions of Fe in each?

12. 62. Which of the following compounds has the highest iron content?
FeCL2
Molar mass = 127g
%Fe + 56/127 X 100 = 44%

13. 62. Which of the following compounds has the highest iron content?
B. Fe(C2H3O2)3 Molar mass = 233g %Fe is 56/233 X 100 = 24%

14. 62. Which of the following compounds has the highest iron content?
C. Fe(OH)2 Molar mass = 90g %Fe is 56/90 X 100 = 62%

15. 62. Which of the following compounds has the highest iron content?
D. FeO Molar mass = 72g %Fe is 56/72 X 100 = 78%

16. 64. Classify each formula as an empirical or a molecular formula
S2Cl2
C6H10O4
Na2SO3
C5H10O5
C17H19NO3
(NH4)2CO3

17. 64. Classify each formula as an empirical or a molecular formula
S2Cl2 M
C6H10O4 M
Na2SO3 E
C5H10O5 M
C17H19NO3 E
(NH4)2CO3 E

18. 66. Determine the molecular formula for each compound
94.1% O ; 5.9% H; molar mass = 34g
40.0% C ; 6.6% H; 53.4% O; molar mass = 120g

19. 66. Determine the molecular formula for each compound
94.1% O ; 5.9% H; molar mass = 34g
.94 X 34g = 32 g O
.059 X 34g = 2 g H
There are two moles of both H and O, so the molecular formula must be H2O2

20. 66. Determine the molecular formula for each compound
40.0% C ; 6.6% H; 53.4% O; molar mass = 120g
.4 X 120 = 48 g C
.066 X 120 = 7.92 g H
.534 X 120 = 64 g O
There are 4 moles of C, 8 moles of H, and 4 moles of O, so the formula must be C4H8O4