Portage Learning CHEM 121 MODULE 2 EXAM
Portage Learning CHEM 121 MODULE 2 EXAM
Ques on 1
Number your answers, and show your work. Be sure to give answers with the correct units. Calculate the
molecular weight of the following compounds:
1. Ca3N2
2. Li3PO4
3. NH4NO3
Answer:
1. Ca3N2 = 3 (40.08) + 2 (14.01) = 148.26
2. Li3PO4 = 3 (6.941) + (30.97) + 4 (16.00) = 115.793
3. NH4NO3 = 2 (14.01) + 4 (1.008) + 3 (16.00) = 80.052
Ques on 2
Number your answers, and show your work. Be sure to give answers with the correct units. Calculate the
number of moles in 10.0 grams in the following compound:
1. NH4NO3
Calculate the number of grams in 0.0500 mol in the following compound: 2.
Li3PO4
Answer:
1. MW of NH4NO3 = 80.052 moles =
10..052 = 0.125 mole 2. MW of
Li3PO4 = 115.793 grams =
Portage Learning CHEM 121 MODULE 2 EXAM 2025
, Portage Learning CHEM 121 MODULE 2 EXAM
0.0500 x 115.793 = 5.79 grams
Ques on 3
Number your answers, and be sure to show your work. Calculate the % composi on of the following
compounds: 1. Na2SO4
2. Ca(NO3)2
Answer:
1. MW of Na2SO4 = 2 (22.99) + (32.07) + 4(16.00) = 142.05
%Na = 45..05 x 100 = 32.37%
%S = 32..05 x 100 = 22.58%
%O = 64..05 x 100 = 45.05%
2. MW of Ca(NO3)2 = (40.08) + 2 (14.01) + 6 (16.00) = 164.1
%Ca = 40..1 x 100 = 24.42%
%N = 28..1 x 100 = 17.07% %O
= 96..1 x 100 = 58.50%
Ques on 4
Number your answers, and be sure to show your work. Determine the empirical formula for the following
compound % composi ons:
1. 52.56% Fe, 2.83% H, 44.91% O
2. 71.98% C, 6.71% H, 21.31% O
Answer:
1) % Composi on of a compound is:
Portage Learning CHEM 121 MODULE 2 EXAM 2025
Portage Learning CHEM 121 MODULE 2 EXAM
Ques on 1
Number your answers, and show your work. Be sure to give answers with the correct units. Calculate the
molecular weight of the following compounds:
1. Ca3N2
2. Li3PO4
3. NH4NO3
Answer:
1. Ca3N2 = 3 (40.08) + 2 (14.01) = 148.26
2. Li3PO4 = 3 (6.941) + (30.97) + 4 (16.00) = 115.793
3. NH4NO3 = 2 (14.01) + 4 (1.008) + 3 (16.00) = 80.052
Ques on 2
Number your answers, and show your work. Be sure to give answers with the correct units. Calculate the
number of moles in 10.0 grams in the following compound:
1. NH4NO3
Calculate the number of grams in 0.0500 mol in the following compound: 2.
Li3PO4
Answer:
1. MW of NH4NO3 = 80.052 moles =
10..052 = 0.125 mole 2. MW of
Li3PO4 = 115.793 grams =
Portage Learning CHEM 121 MODULE 2 EXAM 2025
, Portage Learning CHEM 121 MODULE 2 EXAM
0.0500 x 115.793 = 5.79 grams
Ques on 3
Number your answers, and be sure to show your work. Calculate the % composi on of the following
compounds: 1. Na2SO4
2. Ca(NO3)2
Answer:
1. MW of Na2SO4 = 2 (22.99) + (32.07) + 4(16.00) = 142.05
%Na = 45..05 x 100 = 32.37%
%S = 32..05 x 100 = 22.58%
%O = 64..05 x 100 = 45.05%
2. MW of Ca(NO3)2 = (40.08) + 2 (14.01) + 6 (16.00) = 164.1
%Ca = 40..1 x 100 = 24.42%
%N = 28..1 x 100 = 17.07% %O
= 96..1 x 100 = 58.50%
Ques on 4
Number your answers, and be sure to show your work. Determine the empirical formula for the following
compound % composi ons:
1. 52.56% Fe, 2.83% H, 44.91% O
2. 71.98% C, 6.71% H, 21.31% O
Answer:
1) % Composi on of a compound is:
Portage Learning CHEM 121 MODULE 2 EXAM 2025
