Chemistry- Test 2 Review.docx - 1 A 5.05 g sample of...

1. A 5.05 g sample of quartz (SiO2 ) contains 2.36 g of silicon. What are
the percentages of silicon and oxygen in quartz?
2. How many formula units are in 0.25 mole of Na
2
0?
3. Calculate the molar mass of CuSO
4
•5H
2
0

4. If 8.53 x 10 24 molecules of a substance have a mass of 483 g, what
is the molar mass of the substance?
5. How many oxygen atoms are in 75.0 g of SO
3
?
6. What is the mass of 2.4 x 10
23
molecules of NO
2
?

7. Given the following molecular formulas, determine the
empirical formula of each compound:
N
2
0
5
, PC1
3
, H
2
0
2
, C
6
H
4
Cl
2
8. Acetic acid is the active ingredient in vinegar. It consists of
40.00% C, 6.714% H, and 53.29% 0. What is the empirical
formula of acetic acid?
9. Butyric acid has a very unpleasant odor. It is present in some rotting
foods, body odor and vomit. Butyric acid has a molar mass of 88.10

g/mol and consists of 54.53% C, 9.153% H, and 36.32% 0. What is
the molecular formula of butyric acid?
10. Calculate the molarity of a solution consisting of 75.0 g of
KOH in 2.00 L of solution.