CHEM 108 Module 2 Exam Answers- Portage Learning

Module 2 exam
Exam Page 1
Show the calculation of the molecular weight for the following two compounds, reporting your
answer to 2 places after the decimal.


Ca3(PO4)2
Ca = 40.08
P = 30.97
O = 16
(40.08 x 3) + (30.97 x 2) +(16 x 8) =
(120.24)+ ((61.94) + (128) = 310.18
Answer = 310.18


C9H8NO4Cl
C = 12.01
H=1
N = 14.01
O = 16
Cl = 35.45
(12.01 x 9) +(1 x 8) + (14.01) +( 16 x 4) + (35.45) =
(108.09) + (8) + (14.01) + (64) +(35.45) = 229.55
Answer: 229.55
Answer Key
Show the calculation of the molecular weight for the following two compounds, reporting your
answer to 2 places after the decimal.


Ca3(PO4)2

, 3Ca + 2P + 8O = 310.18


C9H8NO4Cl


9C + 8H + N + 4O + Cl = 229.61
Exam Page 2
Show the calculation of the number of moles in the given amount of the following 2 substances.
Report your answer to 3 significant figures.


13.0 grams of (NH4)2CO3
N = 14.007
H = 1.008
C = 12.011
O = 16
(14.007 x 2) +(1.008 x 8) + (12.011) + (16 x 3) =
(28.014) + (8.064) +(12.011) + (48) = 96.089
13g/96.089 mol/g = .135 mol
Answer .135 mol.


16.0 grams of C8H6NO4Br
C = 12.011
H = 1.008
N = 14.007
O = 16
Br = 79.904
(12.011 x 8) +(1.008 x 6) + (14.007) + ( 16 x 4) + (79.904)
(96.088) +( 6.048) +(14.007) + (64) + (79.904) = 259.967