Assignment 10-1
Molecular Weight & Molar Mass
A. Define molecular weight:
B. Define molar mass:
Determine the molecular weight
Determine the molar mass in grams
in amu of the following substances:
of the following substances.
(Answers at bottom)
(Answers at bottom)
1. H2
2. Mg
3. Au
4. O2
5. Kr
6. CO
7. NaI
8. MgCl2
9. FePO4*2H2O (*means added H2O)
10. Pb(NO3)2
1. Mn
2. Ca
3. CO2
4. BaF2
5. AlCl3*3H2O (*means added H2O)
6. SiO2
7. Hg2O
8. Fe2O3
9. MgSO4
10. Sr(CN)2
Percent Composition Problems - Determine the percentage composition of mass of each element
in the compound relative to the total molecular weight of each compound below.
1. H2O
5. K3PO4 (for strong roots & stems)
2. CO2
6. KNO3 (in gun powder)
3. NaCl
7. NH4NO3 (explosive fertilizer)
4. CaCl2
8. (NH4)2SO4 (greens lawns)
Assignment 10-2
Quantities of Matter: One step conversions with elements
I. Convert to moles.
1. 12.04 x 1023 atoms He
6. 24 grams of carbon
2. 3.01 x 1023 atoms Cu
3. 3.612 x 1023 atoms Fe
4. 100. atoms of Ar
5. 1 atom S
II. Convert to mass in grams.
11. 10.0 moles Na
12. 2.20 moles Sn
13. 5.00 moles Ag
14. 0.000 300 mole of gold
15. 1.00 x 107 moles of boron
7. 59.3 grams of tin
8. 98.9 grams of sodium
9. 4999 grams of potassium
10. 0.005 00 gram of neon
III. Convert to number of atoms
16. 3.00 moles Ar
17. 8.50 moles Fe
18. 25.0 moles Ar
19. 0.001 00 mole of sodium
20. 1.0 x 10-5 mole of aluminum
Assignment 10-3
Quantities of Matter: One step conversions with compounds
I. Convert to moles.
1. 6.02 x 1023 molecules CO2
6. 34 g NH3
2. 1.806 x 1023 molecules Cl2
7. 50.0 g CaCO3
23
3. 1.51 x 10 molecules H2O
8. 360 g H2O
4. 1000 molecules P4O10
9. 9.00 grams of sulfuric acid, H2SO4
5. 1 molecule of NH3
10. 1.00 gram of sodium chloride
II. Convert to mass in grams.
III. Convert to number of molecules.
11.
12.
13.
14.
5.0 moles NH3
4.50 moles NaCl
0.30 mole HCl
0.002 00 mole Na2SO4
15. 1.50 x 10-4 mole silver chloride, AgCl
16.
17.
18.
19.
2.0 moles CO2
1.8 moles PCl3
35.0 moles ammonia, NH3
0.0500 mole sulfur dioxide, SO2
20. 1.00 x 10-3 mole CO
Assignment 10-4
Quantities of Matter: 2 Step Problems
Suggestion: Begin each problem by sketching a diagram that outlines the steps in the solution to
the problem.
I. Convert to mass in grams.
III. Convert to number of molecules.
23
1. 6.02 x 10 atoms Ca
11. 72 grams HCl
2. 1.204 x 1023 atom Bi
3. 3.01 x 1023 atoms Ni
12. 9.0 grams H2O
4. 1000 atoms of aluminum
5. 1 atom of sodium
II. Convert to number of atoms.
13.
14.
15.
IV.
6. 540 grams Al
16.
7. 294 grams Au
17.
8. 6.35 grams Cu
9. 2000. grams of magnesium
10. 1.00 gram of lithium
18.
19.
20.
22 grams CO2
500 grams of nitrogen(II)oxide, NO
1.00 gram CCl4
Convert to mass in grams.
6.02 x 1023 molecules Cl2
3.01 x 1023 molecules SO2
1.81 x 1024 molecules CO2
1000. molecules of hydrosulfuric acid, H2S
1 molecule of water
Assignment 10-5
Calculations Involving Volume of Gasses at STP
Define: a) STP
b) molar volume
What volumes will the following samples occupy at STP?
One step
1. 6.0 moles of O2
Two step
5. 22.0 g of CO2
2.
0.50 moles of CO2
6.
3.01 x 1023 molecules of N2
3.
4.
5.5 moles of ammonia NH3
0.0020 moles of methane, CH4
7.
8.
1.20 x 1023 molecules of NO2
479.4 g of Neon
Mixed problems
9. What volume, in liters, will be occupied by 4.70 moles of helium gas at STP?
10. What is the volume, in liters, occupied by 1.00 x 10-3 mole of ammonia gas, NH3, at STP?
11. How many moles are represented by 38.8 ml of hydrogen gas, H2, at STP?
12. What volume in liters at STP is occupied by 1.80 x 1023 molecules of oxygen, O2, gas?
13. What volume in liters at STP is occupied by 1.00 x 10 20 molecules of methane, CH4, gas?
14. How many molecules of nitrogen dioxide, NO2, are present in 11.2 L of the gas at STP?
15. What volume would 8.0 g of methane (CH4) occupy at STP?
16. What volume would 24.0 g of oxygen gas, O2, occupy at STP?
17. What is the mass of 33.6 L of carbon dioxide, CO2, at STP?
10-1 Answers A
1. 2.0 amu (H2)
2. 24.3 amu
3. 197.0 amu
4. 32.0 amu
5. Kr 83.8 amu
6. 28.0 amu
7. 149.9 amu
8. 95.3 amu
9. 186.8 amu
10. 331.2 amu
10-2 Answers
1. 2.00 mol He
2. 0.500 mol Cu
3. 0.600 mol Fe
4. 1.66 x 10-22 mol Ar
5. 1.66 x 10-24 mol S
6. 2.0 mol C
7. 0.500 mol Sn
8. 4.30 mol Na
9. 128 mol K
B
1. 54.9 g
2. 40.1 g
3. 44.0 g
4. 175.3 g
5. 187.5 g
6. 60.1 g
7. 417.2 g
8. 159.6 g
9. 120.4 g
10. 139.6 g
10-3 Answers
-4
10. 2.47 x 10 mol Ne 1. 1.00 mole CO2
10.
11. 230 g Na
2. 0.300 mole Cl2
11.
12. 261 g Sn
3. 0.251 mole H2O
12.
13. 540 g Ag
4. 1.66 x 10-21 molP4O10
14. 0.0591 g Au
5. 1.66 x 10-24 molNH3 14.
15. 1.08 x 108 g B
6. 2.0 moles NH3
15.
16. 1.81 x 1024 at Ar
7. 0.500 mole CaCO3 16.
24
17. 5.12 x 10 at Fe
8. 20.0 moles H2O
17.
18. 1.50 x 1025 at Ar
9. 0.0918 mole H2SO4 18.
20
19. 6.02 x 10 at Na
19.
1. 40.1 g Ca
2. 41.8 g Bi
3. 29.4 g Ni
4. 4 x 10-20 g Al
13. 11 g HCl
0.284 g Na2SO4
0.0215 g AgCl
1.2 x 1024 mlc CO2
1.1 x 1024 mlc PCl3
2.11 x 1025 mlcNH3
3.01 x 1022 mlc SO2
20. 6.02 x 1020 mlc CO
20. 6.02 x 1018 at Al
10-4 Answers
0.0171 mole NaCl
85 g NH3
263 g NaCl
10-5 Answers
11. 1.2 x 1024 mlc HCl
12. 3.0 x 1023 mlc H2O
13. 3.0 x 1023 mlc CO2
14. 1.00 x 1025 mlc NO
1. 130 L O2
11. 1.73 x 10-3 mol H2
2. 11 L CO2
12. 6.70 L O2
3. 120 L NH3
13. 3.71 x 10-3 L CH4
4. 0.045 L CH4
14. 3.01 x 1023 mlc NO2
5. 3.82 x 10-23 g Na
15. 3.91 x 1021 mlc CCl4 5. 11.2 L CO2
15. 11 L CH4
25
6. 1.20 x 10 atoms Al 16. 71.0 g Cl2
6. 11.2 L N2
16. 16.8 L O2
7. 8.98 x1023 atoms Au 17. 32.1 g SO2
7. 4.47 L NO2
17. 66.0 g CO2
8. 6.02 x 1022 atoms Cu 18. 132 g CO2
8. 532 L Ne
25
-20
9. 4.95 x 10 atoms Mg 19. 5.65 x 10
g H2S 9. 105 L He
10. 8.67 x 1022 atoms Li 20. 2.99 x 10-23 g H2O 10. 2.24 x 10-2 L NH3