CHEM 103 M2: Exam Questions and Correct Answers
Attempt History
Attempt Time Score
LATEST Attempt 1 112 minutes 100 out of 100
.
Question 1 pts
You may find the following resources helpful:
Scientific Calculator (https://www.desmos.com/scientific)
Periodic Table
(https://previous.nursingabc.com/upload/images/Help_file_picture/Periodic_
Equation Table
(https://portagelearning.instructure.com/courses/948/files/271474/download?
download_frd=1)
Show the calculation of the molecular weight for the following
compounds, reporting your answer to 2 places after the decimal.
1. Al2(SO4)3
2. C7H5NOBr
Your Answer:
1. Al2(SO4)3
Al = 2 x 26.98 = 53.96
S = 3 x 32.07 = 96.21
O = 12 x 16.00 = 192
1/18
,Total Molecular Weight for Al2(SO4)3 = 342.17
2. C7H5NOBr
C = 7 x 12.01 = 84.07
H = 5 x 1.008 = 5.04
N = 1 x 14.01 = 14.01
O = 1 x 16.00 = 16.00
Br = 1 x 79.90 = 79.90
Total Molecule Weight for C7H5NOBr= 199.02
1. 2Al + 3S + 12O = 342.17
2. 7C + 5H + N + O + Br = 199.02
Question 2 pts
You may find the following resources helpful:
Scientific Calculator (https://www.desmos.com/scientific)
Periodic Table
(https://previous.nursingabc.com/upload/images/Help_file_picture/Periodic_
Equation Table
(https://portagelearning.instructure.com/courses/948/files/271474/download?
download_frd=1)
Show the calculation of the number of moles in the given amount of the
2/18
, following substances. Report your answerto 3 significant figures.
1. 13.0 grams of (NH4)2CO3
2. 16.0 grams of C8H6NO4Br
Your Answer:
Moles = grams / Molecular Weight
1. 13.0 grams of (NH4)2CO3
Moles = 13.0 g / 96.094 = .135 moles of (NH4)2CO3
N = 2 x 14.01 = 28.02
H = 8 x 1.008 = 8.064
C = 1 x 12.01 = 12.01
O = 3 x 16 = 48
Molecular weight is 96.094
2. 16.0 grams of C8H6NO4Br
Moles = 16.0 g / 260.038 = .0615 moles of C8H6NO4Br
C = 8 x 12.01 = 96.08
H = 6 x 1.008 = 6.048
N = 1 x 14.01 = 14.01
O = 4 x 16.00 = 64
Br = 1 x 79.90 = 79.90
Molecular weight of C8H6NO4Br = 260.038
3/18
Attempt History
Attempt Time Score
LATEST Attempt 1 112 minutes 100 out of 100
.
Question 1 pts
You may find the following resources helpful:
Scientific Calculator (https://www.desmos.com/scientific)
Periodic Table
(https://previous.nursingabc.com/upload/images/Help_file_picture/Periodic_
Equation Table
(https://portagelearning.instructure.com/courses/948/files/271474/download?
download_frd=1)
Show the calculation of the molecular weight for the following
compounds, reporting your answer to 2 places after the decimal.
1. Al2(SO4)3
2. C7H5NOBr
Your Answer:
1. Al2(SO4)3
Al = 2 x 26.98 = 53.96
S = 3 x 32.07 = 96.21
O = 12 x 16.00 = 192
1/18
,Total Molecular Weight for Al2(SO4)3 = 342.17
2. C7H5NOBr
C = 7 x 12.01 = 84.07
H = 5 x 1.008 = 5.04
N = 1 x 14.01 = 14.01
O = 1 x 16.00 = 16.00
Br = 1 x 79.90 = 79.90
Total Molecule Weight for C7H5NOBr= 199.02
1. 2Al + 3S + 12O = 342.17
2. 7C + 5H + N + O + Br = 199.02
Question 2 pts
You may find the following resources helpful:
Scientific Calculator (https://www.desmos.com/scientific)
Periodic Table
(https://previous.nursingabc.com/upload/images/Help_file_picture/Periodic_
Equation Table
(https://portagelearning.instructure.com/courses/948/files/271474/download?
download_frd=1)
Show the calculation of the number of moles in the given amount of the
2/18
, following substances. Report your answerto 3 significant figures.
1. 13.0 grams of (NH4)2CO3
2. 16.0 grams of C8H6NO4Br
Your Answer:
Moles = grams / Molecular Weight
1. 13.0 grams of (NH4)2CO3
Moles = 13.0 g / 96.094 = .135 moles of (NH4)2CO3
N = 2 x 14.01 = 28.02
H = 8 x 1.008 = 8.064
C = 1 x 12.01 = 12.01
O = 3 x 16 = 48
Molecular weight is 96.094
2. 16.0 grams of C8H6NO4Br
Moles = 16.0 g / 260.038 = .0615 moles of C8H6NO4Br
C = 8 x 12.01 = 96.08
H = 6 x 1.008 = 6.048
N = 1 x 14.01 = 14.01
O = 4 x 16.00 = 64
Br = 1 x 79.90 = 79.90
Molecular weight of C8H6NO4Br = 260.038
3/18
