1. Chemical Composition Stoichiometry Review

2. How many moles of Ca are 3.01  1023 atoms of calcium?
6.1
3.01 mol
1.81  1047 mol
1.00 mol
0.500 mol
3.01  1023 mol
Answer: d

3. How many grams are in 1.000 mol of iron?
6.3
1.000 g
6.022  1023 g g
26.00 g
55.85 g
Answer: e

4. What is the molar mass of ammonium nitrate?
6.4
g/mol
80.05 g/mol
66.04 g/mol
g/mol
95.23 g/mol
Answer: b

5. What is the mass of 4.55  1023 copper atoms?
6.6
4.55 g
4.31  1045 g
1.18  10–2 g
6.02  1023 g
48.0 g
Answer: e

6. How many moles are in 5.672 g of iron(III) sulfate?
6.7
3.730  10–2 mol
2.268  10–3 mol
2.268  103 mol
5.672  10–3 mol
1.418  10–2 mol
Answer: e

7. How many moles are in 5.6 g of lithium nitride?
6.9
0.27 mol
0.20 mol
0.16 mol
0.56 mol
2.0  102 mol
Answer: c

8. How many moles of oxygen are in 3.45 mol of diphosphorus pentoxide?
6.11
6.90 mol O
3.45 mol O
5.75 mol O
13.5 mol O
17.3 mol O
Answer: e

9. What is the mass of 5.660 mol of dinitrogen tetrahydride?
6.14
90.70 g g
5.66 g
181.4 g
0.353 g
Answer: d

10. An unknown compound has a molar mass of 118. 10 g/mol
An unknown compound has a molar mass of g/mol. Given the following mass percent composition, calculate the empirical and molecular formulas: 40.7% C, 5.13% H, and 54.2% O.
6.19
CH1.5O and C2H3O2
C3H5O3 and C6H10O6
C4H6O4 and C8H12O8
C4H6O4 and C2H3O2
C2H3O2 and C4H6O4
Answer: e

11. What is the empirical formula of ascorbic acid, C6H8O6, a compound found in citrus fruits?
6.22
C6H8O6
C4H4O4
C3H4O3
CHO
CH2O
Answer: c

12. Identify the diatomic molecule that has a mass of 33
Identify the diatomic molecule that has a mass of g and contains moles of molecules.
6.23 H2 N2 O2 F2
Cl2
Answer: d

13. Calculate the empirical formula of a 5
Calculate the empirical formula of a 5.85 g sample of an unknown chromium oxide containing 4.00 g of chromium.
6.24
Cr2O7
Cr2O4
CrO
CrO1.5
Cr2O3
Answer: e

14. What is the empirical formula of a compound that contains 14
What is the empirical formula of a compound that contains 14.5% hydrogen and 85.5% carbon by mass?
6.25 CH
CH2
C2H
C2H3
CH3
Answer: b

15. What is the mass percentage of oxygen in glycerol, C3H8O3?
6.26
6.25%
26.08%
54%
52.12%
64.32%
Answer: b

16. The empirical formula of a compound is found to be CH2O
The empirical formula of a compound is found to be CH2O. If its molar mass is g/mol, what is the molecular formula of the compound?
6.27
CH2O
C3H6O3
C6H12O6
C2H4O2
None of the above
Answer: c

17. A variety of Freon contains 69. 58% chlorine by mass
A variety of Freon contains 69.58% chlorine by mass. How many grams of chlorine are contained in 11.3 g of this substance?
6.28
7.86 g
5.35 g
7.863 g g
None of the above
Answer: a

18. What is the mass percentage of oxygen in potassium chlorate?
6.29
6.527%
13.06%
19.60%
39.17%
None of the above
Answer: d

19. A compound is found to contain 60. 00% C, 4. 48% H and 35. 53% O
A compound is found to contain 60.00% C, 4.48% H and 35.53% O. What is its empirical formula?
6.30
C9H8O4
C3H2O
C2H2O2
C2H2O
None of the above
Answer: a