Name: _______________________________________
I.
Chapter 11: Chemical Quantities
Test Review
Calculate the molar mass or gram formula mass for the following. Include units.
1. sodium chloride - NaCl – 58.5 g/mol
II.
4. Carbon Dioxide – CO2 – 44.0 g/mol
2. water – H2O – 18.0 g/mol
5. calcium chloride – CaCl2 – 111 g/mol
3. calcium nitrate - Ca(NO3)2 – 164 g/mol
6. ammonium sulfate – (NH4)2SO4 – 132 g/mol
Definitions of the Mole. Fill in the blank with the appropriate quantity.
7. 1 mole = __6.02 x 1023____ particles
8. 1 mole Aluminum = ____27.0______ grams (gfm/molar mass of the specific substance)
III.
Mole Conversions: Convert the following quantities to Moles. SHOW YOUR WORK!
9.
10.
86.4 g FeO –
86.4 g FeO
1 mol FeO
= 1.20 mol FeO
71.84 g FeO
10.4 g CO2
1 mol CO2
= 0.236 mol CO2
44.01 g CO2
10.4 g CO2 –
11. 1.42 x 1042 particles
1.42 x 1042 particles
1 mol
= 2.36 x 1018 mol
23
6.02 x 10 particles
Mole Conversions: Convert the following moles to the appropriate quantity. SHOW YOUR WORK!
Include units on answers.
12. 10.0 grams lead (II) hydroxide (convert to formula units) = 2.50 x1022 formula units Pb(OH)2
10 g Pb(OH)2
1 mol Pb(OH)2
6.02 x 10 Pb(OH)2 =
241 g Pb(OH)2
1 mol Pb(OH)2
13.
0.40 moles aspirin (C9H8O4) (convert to grams) – 72 g C9H8O4
0.40 mol C9H8O4
14.
180.12 g C9H8O4
1 mol C9H8O4
=
1.86 x 1025 molecules CO2 (convert to grams) = 1360 g CO2 or 1.36 x103 g CO2
1.86 x 1025 molecules CO2
1 mol CO2
6.02 x 1023 molecules CO2
44.0 g CO2
=
1 mol CO2
Name: _______________________________________
IV.
Percent Composition: Determine the % Composition for the following compounds. Show your
work.
15. C2H5
16. Ca(OH)2
% C = 24.0 x100 = 82.5% C
29.1
%Ca = 40.1 x 100 = 54.1% Ca
74.1
% H = 5.05 x 100 = 17.4% H
29.1
% O = 32.0 x 100 = 43.2% O
74.1
% H = 2.02 x 100 = 2.73% H
74.1
17. A compound contains 25 g Sulfur and 75 g of oxygen. USE GIVEN MASSES
% S = 25 x 100 = 25%
100
% O = 75 x 100 = 75%
100
V.
Determine the empirical formula for the following. Show your work. Remember POEM!!!
18. 39.8 % C, 6.7 % H, 53.5 % O
39.8g 1 mol = 3.31 = 1
6.7
12.01
3.31
1 mol = 6.65 = 2
1.01
3.31
19. 24.7% K, 34.8 % Mn, 40.5 % O
24.7 g 1 mol = 0.63 = 1
34.8 g Mn 1 mol
39.10
0.63
54.94 g
VI.
empirical formula: ___CH2O____
53.5 1 mol = 3.35 = 1
16.00 3.31
empirical formula: ___KMnO4__
= 0.63 = 1
40.5 g 1 mol = 2.53 = 4
0.63
16.00 0.63
Determine the molecular formula from the empirical formula. Show your work.
20. Empirical formula = CH4
n=
molecular mass = 80 g/mol
80 g/mol
16.0
= 5
21. Empirical formula = CH2O
n =
270 g/mol
30.0
= 9
molecular formula: ___C5H20_____
multiply all subscripts in Empirical Formula by 5
molecular mass = 270 g/mol
molecular formula:__C9H18O9___
multiply all subscripts in Empirical Formula by 9
22. Which of the following substances have the same empirical formula? Choose all that apply.
a. CH
b. CH2O
c. C6H6
d. C2H4
e. C2H2
Name: _______________________________________
Review Sheet Chapter 11: The Mole
Mole Conversions, % Composition, Empirical & Molecular Formulas & Hydrates
1. What is the mass in grams of 0.42 mole of barium chloride?
BaCl2
0.42 mol BaCl2
208 g BaCl2 = 87 g BaCl2
1 mol
1(137) + 2(35.5) = 208 g/mol
2. In a chemical reaction, 0.397 moles of ethyl chloride (C2H5Cl) is produced. What is the mass in grams
of this amount?
0.397 mol C2H5Cl 64.6 g C2H5Cl
= 25.6 g C2H5Cl
1 mol C2H5Cl
(C2H5Cl)
2(12.0) + 5(1.01) + 1(35.5) = 64.6 g/mol
3. A chemist plans to use 435 g of Ammonium Nitrate in a reaction. How many moles is this?
NH4NO3
435 g NH4NO3
1 mol NH4NO3
80.0 g NH4NO3
= 5.44 mol NH4NO3
2(14.0) +1(4) +3(16) = 80.0g/mol
4. A small bottle in the chemistry stockroom contains 43.25 g of Nickel (II) carbonate, how many moles is
this?
43.25 g NiCO3
1 mol NiCO3 6.02 x 1023 formula units = 2.188 E23 formula
119 g NiCO3
1 mol
units
NiCO3
1(58.7) + 1(12.0) + 3(16) = 119 g/mol
5. A nurse has been asked to get 0.0465 moles of quinine (C20H24N2O2). What mass should the nurse
obtain?
0.0465 moles C20H24N2O2
324 g C20H24N2O2
1 mol C20H24N2O2
= 15.1 g C20H24N2O2
20(12) + 24(1.01) + 2(14.0) + 2(16.0) = 324 g/mol
6. During an electroplating process, 5.8625 g of silver are deposited on a steel bar. How many atoms is
this?
5.8626 g Ag
1 mol Ag
6.02 x 1023 atoms
= 3.2678 E22
108 g Ag
1 mol Ag
7. How many moles are present in 1.0 x 1020 atoms F?
1.0 x 1020 atoms F
1 mol F
23
6.02 x 10 atoms F
= 1.7 x 10-4 mol F
8. How many atoms are present in 2.4 moles Silver oxide?
2.4 mol Ag2O 6.02 x 1023 formula units Ag2O = 1.4 x 1024 formula units Ag2O
1 mol Ag2O
9. Calculate the molar mass / gram formula mass for the following compounds:
Name: _______________________________________
a. sodium nitrate – NaNO3 = 1(23.0) + 1(14.0) + 3(16.0) = 85.0 g/mol
b. magnesium phosphate – Mg3(PO4)2 = 3(24.3) + 2(31.0) + 8(16.0) = 263 g/mol
c. calcium chloride – CaCl2 = 111 g/mol See Page 1 for work
d. sulfuric acid – H2SO4 = 2(1.01) + 1(32.1) + 4(16.0) = 98.1 g/mol
10. Determine the % composition of nitrogen and hydrogen in ammonia (NH3).
14.0 + 3(1.01) = 17.0g/mol
%N = 14.0 x 100 = 82.4.% N
%H = 3.03 x 100 = 17.8% H
17.0
17.0
11. Calculate the % composition of K3PO4.
3(39.1) + 1(31.0) + 4(16.0) = 212 g/mol
%K = 117
x 100 = 55.2% K
%P = 31.0
x 100 = 14.6% P
212
212
%O =
64 x 100 = 30.2%O
212
12. Determine the empirical formula of a compound that contains 69.5% oxygen and 30.5% nitrogen.
69.5 g O
1 mol O
= 4.34 mol O = 2 mol O
16.0 g O
2.18
NO2
30.5 g N
1 mol N
= 2.18 mol N = 1 mol N
14.0 g N
2.18
13. The molecular mass of a compound is 166.3 g. The compound contains 47.1% K, 14.5 % C and 38.4 %
O. What is the molecular formula for this compound? (Hint: determine the empirical formula first.)
47.1 g K
1 mol K
39.1 g K
= 1.21 mol K = 1 mol K
1.21
14.5 g C
38.4 g O
1 mol O
16.0 g O
KCO2 empirical
1(39.1) + 1(12.0) + 2(16.0) = 83.1g/mol
1 mol C
12.0 g C
= 1.21 mol C = 1 mol C
1.21
= 2.40 mol O = 2 mol O
1.21
n = 166.3given
=2
83.11empirical MM
K2C2O4
14. Determine the molecular formula if the empirical formula is CH2O and the molecular mass is 180 g/mol.
CH2O 1(12.0) + 2(1.01) + 1(16.0) = 30.0g/mol
‘n’ = 180 g/mol =
30.0 g/mol
6
C6H12O6
Multiply 6 by the
subscripts in empirical
formula