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104 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 10
Chapter 10 Review
39. Explain in detail how it is possible to count atoms, ions,
formula units, and molecules by measuring mass.
40. Why must a chemist be able to count particles of matter?
41. How is the molar mass of a compound related to the atomic
masses of the atoms in the compound?
42. The atomic mass of nitrogen is 14.007 amu. What is the mass
in grams of a mole of N 2 molecules?
43. An analysis of silicon dioxide (SiO 2 ) found in beach sand in
California shows that it is 46.74% silicon and 53.26% oxygen.
Can you assume that silicon dioxide found in a quartz rock in
Michigan will have the same analysis? Explain your answer.
44. The empirical formula for a certain compound is found to be
C 2 H 4 O. From this information, what can you predict about the
molecular formula for the compound?
45. The formula for magnesium bromide hexahydrate is
MgBr 2 и 6H 2 O. This compound could be represented by the formula MgBr 2 H 12 O 6 . Explain why this formula is almost never
used.