Chapter 03 – Mass Relationships in Chemical Reactions
Chapter 03
Mass Relationships in Chemical Reactions
1. An atom of helium has a mass about four times greater than that of an atom of hydrogen.
Which choice makes the correct comparison of the redative numbers of helium and hydrogen
atoms in equal masses of the two elements?
Chapter 03 – Mass Relationships in Chemical Reactions
2. There are two stable isotopes of chlorine: chlorine-35, with a mass of 34.968853 amu; and
chlorine-37, with a mass of 36.965903. Given that the average atomic mass of a chlorine atom
is 35.45 amu, which of the following statements is true?
Chapter 03 – Mass Relationships in Chemical Reactions
3. An atom of bromine has a mass about four times greater than that of an atom of neon.
Which choice makes the correct comparison of the relative numbers of bromine and neon
atoms in 1,000 g of each element?
4. An atom of bromine has a mass about four times greater than that of an atom of neon. How
many grams of neon will contain the same number of atoms as 1,000 g of bromine?
Chapter 03 – Mass Relationships in Chemical Reactions
5. An average atom of uranium (U) is approximately how many times heavier than an atom of
potassium?
6. Boron obtained from borax deposits in Death Valley consists of two isotopes. They are
boron-10 and boron-11 with atomic masses of 10.013 amu and 11.009 amu, respectively. The
atomic mass of boron is 10.81 amu (see periodic table). Which isotope of boron is more
abundant, boron-10 or boron-11?
Chapter 03 – Mass Relationships in Chemical Reactions
7. The element oxygen consists of three naturally occurring isotopes: 16O, 17O, and 18O. The
atomic mass of oxygen is 16.0 amu. What can be implied about the relative abundances of
these isotopes?
8.
Calculate the average atomic mass of lithium using the following data:
Chapter 03 – Mass Relationships in Chemical Reactions
9.
Calculate the average atomic mass of silver using the following data:
10. What is the average mass of one S atom?
Chapter 03 – Mass Relationships in Chemical Reactions
11. What is the molecular mass of Br2?
12. What is the average mass of one Ca atom?
13. What is the average mass, in grams, of one Zn atom?
Chapter 03 – Mass Relationships in Chemical Reactions
14. What is the average mass, in grams, of one Rb atom?
15. What is the mass of 3.50 x 1024 Ti atoms?
16. What is the mass of 4.50 x 1022 Cu atoms?
Chapter 03 – Mass Relationships in Chemical Reactions
17. If 0.274 moles of a substance weighs 62.5 g, what is the molar mass of the substance, in
units of g/mol?
18. One mole of iron
Chapter 03 – Mass Relationships in Chemical Reactions
19. Which one of the following does not represent 1.000 mol of the indicated substance?
20. How many Br atoms are in 2.50 g of Br?
Chapter 03 – Mass Relationships in Chemical Reactions
21. How many C atoms are in 5.50 g of C?
22. Determine the number of moles of aluminum in 96.7 g of Al.
Chapter 03 – Mass Relationships in Chemical Reactions
24. A gold wire has a diameter of 1.00 mm. What length of this wire contains exactly 1.00
mol of gold? (density of Au = 17.0 g/cm3)
25. A silver wire has a diameter of 0.500 mm. What length of this wire contains exactly 1.00
mol of silver? (density of Ag = 10.5 g/cm3)
Chapter 03 – Mass Relationships in Chemical Reactions
26. A copper wire has a diameter of 2.00 mm. What length of this wire contains exactly 1.00
mol of copper? (density of Cu = 8.92 g/cm3)
27. How many F atoms are in 5.54 g of F2?
Chapter 03 – Mass Relationships in Chemical Reactions
29. How many Cl atoms are in 0.0728 g of PCl3?
30. How many moles of CF4 are there in 171 g of CF4?
31. How many moles of NH3 are there in 77.5 g of NH3?
Chapter 03 – Mass Relationships in Chemical Reactions
32. Calculate the number of moles of cesium in 50.0 g of cesium.
33. Which of the following samples contains the greatest number of atoms?
34. Which of the following CO2 samples contains the greatest number of moles of CO2?
Chapter 03 – Mass Relationships in Chemical Reactions
36. Calculate the molar mass of Ba(NO3)2.
37. Calculate the molar mass of (NH4)2SO4.
Chapter 03 – Mass Relationships in Chemical Reactions
38. Calculate the molecular mass of menthol, C10H20O.
39. What is the molar mass of acetaminophen, C8H9NO2?
40. What is the molecular mass of nicotine, C10H14N2?
Chapter 03 – Mass Relationships in Chemical Reactions
42. Calculate the mass of 3.00 moles of CF2Cl2.
43. Calculate the mass of 4.50 moles of Ca3PO4.
Chapter 03 – Mass Relationships in Chemical Reactions
44. Calculate the mass of 0.00456 moles of (NH4)2SO4.
45. The molecular formula of aspirin is C9H8O4. How many aspirin molecules are present in
one 500-milligram tablet?
Chapter 03 – Mass Relationships in Chemical Reactions
46. Formaldehyde has the formula CH2O. How many molecules are there in 0.11 g of
formaldehyde?
47. How many molecules are there in 8.0 g of ozone, O3?