1. Test Review: The Mole

2. Non-Calculator Practice
All of the problems can be solved with simple operations.
Addition
Subtraction
Multiplication
Division
Ratios
Round when needed.

3. What is the molar mass of calcium oxide (in two significant figures)?
CaO
56 g/mol

4. About how many moles of calcium oxide are in 280g?
CaO
56 g/mol
5.0 moles CaO

5. How many calcium ions are in 1 mole of calcium oxide?
CaO
1mole CaO = 1 mole Ca+2 ions
6.022x1023 Ca+2 ions

6. What is the molar mass of sulfur tetraoxide (in two significant figures)?
96 g/mol

7. Approximately what percentage of the mass of sulfur tetraoxide is sulfur (in two significant figures)?
SO4
96 g/mol
33%

8. How many atoms of oxygen would be in 125 molecules of SO4?
1 mole SO4 = 4 atoms of oxygen
500. or 5.00x102 atoms O

9. A compound is 94% sulfur and 6% hydrogen by mass
A compound is 94% sulfur and 6% hydrogen by mass. What is its empirical formula? *remember the rhyme
H2S

10. What is that compound’s molecular formula given its molar mass of 102 g/mol?
H2S
102/34 = 3
H6S3

11. What is the molar mass of lithium chloride?
LiCl
42 g/mol

12. What is the molar mass of ammonium hydroxide?
NH4(OH)
35.06 g/mol

13. Calculate the mass of 0.75 moles of sulfur
24 g Sulfur

14. What percent of zinc nitrate is oxygen?
Zn(NO3)2
50.7 %

15. How many atoms are in 1. 25 moles of dysprosium (Dy). A. 6
How many atoms are in 1.25 moles of dysprosium (Dy)? A E 23 atoms C E 23 atoms B E 23 atoms D E 24 atoms
B x1023 atoms Dy

16. Approximately what is the percentage of carbon in propane. A. 55%. C
Approximately what is the percentage of carbon in propane? A. 55% C. 80% B. 60% D. 70%
C3H8
C. 81.7%

17. What is the empirical formula for C4H10 ?

18. What is the empirical formula of compound with the following percent composition: **remember the rhyme** 43.0% Sr 25.5% Cr 31.4% O
SrCrO4

19. The empirical formula for a compound is CH2 and its molar mass is 98
The empirical formula for a compound is CH2 and its molar mass is g/mol. What is the compound’s molecular formula?
C7H14

20. The empirical formula for a compound is CHBr and its molar mass is 278
The empirical formula for a compound is CHBr and its molar mass is g/mol. What is the compound’s molecular formula?
C3H3Br3

21. Calculator Practice

22. How many atoms are present in 0.270 g of carbon?
Mass-Mole-Particle
1.35 E 22 atoms C

23. What is the molar mass of strontium chloride?
SrCl2
g/mol

24. Calculate the mass of 3.50 x1012 molecules of sulfur dioxide
Particle-Mole-Mass
3.72 x g SO2

25. What is the mass of 5.12 E 24 molecules of oxygen gas?
Particle-Mole-Mass
272 g O2

26. Calculate the mass of 4.5 E 25 molecules of CH4
Particle-Mole-Mass
1200 g CH4

27. What is the molar mass of iron (III) chlorite?
Fe(ClO2)3
g/mol

28. How many grams does 0.500 moles of CuBr weigh?
Mole-Mass conversion
31.8 g

29. What is the mass of 2.4 x 1024 molecules of water?
72 g of H2O

30. How many oxygen atoms does 5
How many oxygen atoms does 5.60 x 1022 molecules of silicon dioxide contain?   
SiO2
2 oxygen atoms: 1 molecule SiO2
1.12 E 23

31. A hydrate of Na2CO3 has a mass of 4. 31 g before heating
A hydrate of Na2CO3 has a mass of 4.31 g before heating. After heating, the mass of the anhydrous compound is found to be 3.22 g. Determine the formula of the hydrate and then write out the name of the hydrate. 
Na2CO3 · 2H2O
sodium carbonate dihydrate