Chapter 3 Problem Set

  1. An element has four naturally occurring 32X (95%), 33X(0.76%), 34X(4.22%), and 36X(0.014%). The masses of the isotopes are 31.97 amu, 32.97 amu, 33.97 amu, and 35.97 amu respectively. Calculate the average atomic mass and identify the element.
  2. How many moles are in a sample of 300 atoms of nitrogen? How many grams?
  3. If you buy 38.9 moles of M&M’s©, how many candies do you have?
  4. Find the mass of 1.16 x 1022 atoms of zinc.
  5. Calculate the molar masses of each of the following compounds:
  6. Cu2SO4
  7. NH4OH
  8. C10H16O
  9. Zr(SeO3) 2
  10. Ca2Fe(CN)6∙12H2O
  11. Cr4(P2O7)3
  12. How many milligrams of Bromine are in 4.8 x 1020 molecules?
  13. How many moles of Cadmium bromide, CdBr2, are in a 39.25 g sample?
  14. Bauxite, the principle ore used in the production of aluminum cans, has a molecular formula Al2O3∙H2O
  15. Find the molar mass of bauxite
  16. How many grams of Al are in 0.58 moles of bauxite?
  17. How many atoms of Al are in 0.58 moles of bauxite?
  18. What is the mass in grams of 2.1 x 1024 molecules of bauxite?
  19. Calculate the mass percent of chlorine in each of the following:
  20. ClF
  21. HClO2
  22. CuCl2
  23. PuOCl
  24. Find the mass percent of each element in C5H10O.
  25. Chlorophyll a is essential for photosynthesis. It contains 2.72% Magnesium by mass. What is the molar mass of chlorophyll a if there is one atom of magnesium in every one molecule of chlorophyll a?
  26. Indicate the formulas below that could be empirical:
  27. CH4
  28. CH2
  29. KMnO4
  30. N2O5
  31. B2H6
  32. NH4Cl
  33. Sb2S3
  34. N2O4
  35. CH2O
  36. The analysis of rocket fuel showed that it contained 87.4% Nitrogen, and 12.6% Hydrogen. Mass spectral analysis showed the fuel to have a molar mass of 32.05 grams. What are the empirical and molecular formulas of the fuel?
  37. Using the data provided, calculate the empirical formulas for the following:
  38. An oxide of nitrogen, which contains 6.35 g of Nitrogen and 3.65 g Oxygen
  39. An oxide of copper, one gram of which contains 0.7989 g copper
  40. An oxide of carbon that contains 42.84% Carbon
  41. A compound of potassium chloride, and oxygen containing 31.97% K and 39.34% O
  42. A compound of hydrogen, carbon, and nitrogen containing 3.70% Hydrogen, 44.44% Carbon, and 51.85% Nitrogen.
  43. What mass of water vapor can be generated from the combustion of 18.74 g ethanol?
  44. How many grams of oxygen are necessary to completely react with 22.8 g of methane?
  45. How many grams of precipitate (Hg2Cl2) would be formed from a solution containing 102.9 g of mercury ions react with chloride ions as follows:

2Hg++2Cl-→ Hg2Cl2

  1. A reaction combines with 133.484 g of lead (II) nitrate with 45.010g of Sodium hydroxide.
  2. How much Sodium hydroxide is formed?
  3. What is the limiting factor? What is the excess reactant?
  4. How much of the excess reactant is left over?
  5. If the actual yield were 80.02 g, what is the percent yield?
  6. What element is the current atomic weight standard?
  7. How many atoms of uranium are present in 1 ng of uranium?
  8. Calculate the molecular formula of a compound containing 48.8% Cd, 20.8% C, 2.62% H, 27.8 % O, and a molecular weight of 460.8 g/mol.
  9. Identify the limiting reactant and determine the mass of the excess reactant left over when 12.00 g of Carbon tetrachloride react with 5.00 g of Chromium(III) oxide via the following reaction:

Cr2O3+CCl4→CrCl3+COCl2