#### Transcript HW3 - skylinecpchemistry

```HW3
58. What is the density of each of
these gases at STP?
A. C3H8
B. Ne
C. NO2
58. What is the density of each of
these gases at STP?
A. C3H8
B. Ne
C. NO2
molar mass = 44 g
molar mass = 20.2
molar mass = 46 g
Molar volume is 22.4 L
58. What is the density of each of
these gases at STP?
A. C3H8
B. Ne
C. NO2
44g / 22.4L= 1.96 g/L
20.2g / 22.4L= .90 g/L
46g / 22.4L= 2.05 g/L
60. Calculate the percent composition
of each compound
A.
B.
C.
D.
H2S
(NH4)2C2O4
Mg(OH)2
Na3PO4
60. Calculate the percent composition
of each compound
A. 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%
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%
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%
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%
62. Which of the following compounds
has the highest iron content?
A.
B.
C.
D.
FeCL2
Fe(C2H3O2)3
Fe(OH)2
FeO
62. Which of the following compounds
has the highest iron content?
A.
B.
C.
D.
FeCL2
Fe(C2H3O2)3
Fe(OH)2
FeO
What are the molar masses?
What are the percent compositions of Fe in each?
62. Which of the following compounds
has the highest iron content?
A. FeCL2
Molar mass = 127g
%Fe + 56/127 X 100 = 44%
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%
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%
62. Which of the following compounds
has the highest iron content?
D. FeO
Molar mass = 72g
%Fe is 56/72 X 100 = 78%
64. Classify each formula as an
empirical or a molecular formula
A.
B.
C.
D.
E.
F.
S2Cl2
C6H10O4
Na2SO3
C5H10O5
C17H19NO3
(NH4)2CO3
64. Classify each formula as an
empirical or a molecular formula
A.
B.
C.
D.
E.
F.
S2Cl2
C6H10O4
Na2SO3
C5H10O5
C17H19NO3
(NH4)2CO3
M
M
E
M
E
E
66. Determine the molecular formula
for each compound
A. 94.1% O ; 5.9% H; molar mass = 34g
B. 40.0% C ; 6.6% H; 53.4% O; molar mass = 120g
66. Determine the molecular formula
for each compound
A. 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
66. Determine the molecular formula
for each compound
B. 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
```