General Chemistry 11th Edition by Darrell Ebbing – Test Bank

 

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Sample Test

Chapter_03_Calculations_with_Chemical_Formulas_and_Equations     1. The molecular formula of a particular solid is C8H4O6. Its molecular mass is   a. 288 amu.   b. 100 amu.   c. 296 amu.   d. 196 amu.   e. 170 amu.   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.67 – Calculate the formula mass from a formula. (Example 3.1) TOPICS:   mass and moles of substance stoichiometry KEYWORDS:   molecular mass OTHER:   general chemistry

 

2. The hydrocarbon octane has the structural formula CH3(CH2)6CH3.  What is the molecular mass of this hydrocarbon?   a. 114.2 amu.   b. 0.008754 amu.   c. 100.1 amu.   d. 0.009984432 amu.   e. 124.2 amu.   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.68 – Calculate the formula mass from a formula. TOPICS:   mass and moles of substance stoichiometry

 

3. A single molecule of polystryene has the repeating unit -[CH2CH(C6H5)]n-, where n is the number of repeating units.  What is the value of n if the molecular mass of a single polymer chain is  amu?   a.   units.   b.  units.   c.  units.   d.  units.   e.  units.   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.68 – Calculate the formula mass from a formula. TOPICS:   stoichiometry mass and moles of substance

 

4. The formula mass of aluminum oxalate, Al2(C2O4)3, is   a. 143 amu.   b. 318 amu.   c. 290 amu.   d. 204 amu.   e. 197 amu.   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.67 – Calculate the formula mass from a formula. (Example 3.1) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   formula mass OTHER:   general chemistry

 

5. The formula mass of zinc acetate trihydrate, Zn(CH3COO)2 • 3H2O, is   a. 356 amu.   b. 184 amu.   c. 292 amu.   d. 238 amu.   e. 156 amu.   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.67 – Calculate the formula mass from a formula. (Example 3.1) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   formula mass OTHER:   general chemistry

 

6. The fully hydrated form of sodium sulfate is the decahydrate, Na2SO4 • 10H2O.  When heated the hydrated salt loses water.  How many water molecules are found per formula unit in a partially dehydrated sample of sodium sulfate with a formula mass of 197 amu (i.e. find n for  Na2SO4 • nH2O)?   a. 3 waters.   b. 5 waters.   c. 7 waters.   d. 9 waters.   e. 4 waters.   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.68 – Calculate the formula mass from a formula. TOPICS:   stoichiometry mass and moles of substance

 

7. What is the molecular mass of cycloheptane, C7H14?   a. 13.02 amu   b. 1191.19 amu   c. 85.08 amu   d. 98.19 amu   e. 26.12 amu   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.67 – Calculate the formula mass from a formula. (Example 3.1) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   molecular mass OTHER:   general chemistry

 

8. What is the formula mass of barium phosphate, Ba3(PO4)2?   a. 506.95 amu   b. 570.95 amu   c. 232.30 amu   d. 1013.90 amu   e. 601.92 amu   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.67 – Calculate the formula mass from a formula. (Example 3.1) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   formula mass OTHER:   general chemistry

 

9. What is the molecular mass of the hydrocarbon styrene (shown in the figure)?   a. 104.1 amu.   b. 91.1 amu.   c. 103.1 amu.   d. 13.0 amu.   e. 78.1 amu.   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.1 LEARNING OBJECTIVES:   GENE.EBBI.13.69 – Calculate the formula mass from molecular models. (Example 3.2) TOPICS:   mass and moles of substance stoichiometry KEYWORDS:   molecular mass OTHER:   general chemistry

 

10. What is the molar mass of ammonium sulfite, (NH4)2SO3?   a. 98 g/mol   b. 116 g/mol   c. 55 g/mol   d. 180 g/mol   e. 84 g/mol   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   mass and moles of substance stoichiometry KEYWORDS:   formula weight OTHER:   general chemistry

 

11. What is the molar mass of zinc sulfate hexahydrate, ZnSO4 • 6H2O?   a. 180. g/mol   b. 270. g/mol   c. 366 g/mol   d. 162 g/mol   e. 564 g/mol   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   mass and moles of substance stoichiometry KEYWORDS:   formula weight OTHER:   general chemistry

 

12. Plastic wrap can be made from poly(vinylidene chloride).  A single poly(vinylidene chloride) strand has the general formula -(CH2CHCl)n-,  where n ranges from 10,000 to 100,000.  What is the molar mass of a single poly(vinylidene chloride) molecule containing  repeating units?   a.  g/mol   b.  g/mol   c.  g/mol   d.  g/mol   e.  g/mol   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   stoichiometry mass and moles of substance

 

13. The dicarboxylic acid potassium hydrogen pthalate (shown in the figure) is used to standardize solutions of strong base.  What is the molar mass of this compound?   a. 204.2 g/mol   b. 192.2 g/mol   c. 248.9 g/mol   d. 71.08 g/mol   e. 172.2 g/mol   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   stoichiometry mass and moles of substance

 

14. What is the molar mass of the solid C6H8N2O4?   a. 144 g/mol   b. 108 g/mol   c. 172 g/mol   d. 90 g/mol   e. 164 g/mol   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   molecular mass OTHER:   general chemistry

 

15. ​A 1.74 g sample of an element contains 7.887 ×1021atoms. What is the element symbol?   a. ​Cs   b. ​I   c. ​In   d. ​Sb   e. ​Cd   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   stoichiometry | determining chemical formulas

 

16. Monodisperse polyacrylonitrile contains molecules with the general formula -(CH2CHCN)n-, where n is typically greater than 10,000.  Given that a sample of monodisperse polyacrilonitrile weighs 676.8 g and contains  molecules of -(CH2CHCN)n-, calculate n.   a.   b.   c.   d.   e.   ANSWER:   a POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   stoichiometry mass and moles of substance

 

17. Monodisperse polyacrylonitrile contains molecules with the general formula -(CH2CHCN)n-, where n is typically greater than 10,000.  Given that a sample of monodisperse polyacrylonitrile weighs 665.1 g and contains  molecules of -(CH2CHCN)n-, what is the molar mass of the polymer?   a.  g/mol   b.  g/mol   c.  g/mol   d.  g/mol   e.  g/mol   ANSWER:   e POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.70 – Understand how the molar mass is related to the formula weight of a substance. TOPICS:   stoichiometry mass and moles of substance

 

18. An atom of an element weighs 3.38× 10–23 g. What is the atomic mass of this element in atomic mass units?   a. 19.6 amu   b. 18.6 amu   c. 17.9 amu   d. 20.3 amu   e. 17.2 amu   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.71 – Calculate the mass of atoms and molecules. (Example 3.3) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

19. What is the mass in grams of one propene, C3H6, molecule?   a. 6.99× 10–23 g   b. 2.53 × 1025 g   c. 44.0 g   d. 42.0 g   e. 1.99 × 10–23 g   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.71 – Calculate the mass of atoms and molecules. (Example 3.3) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

20. What is the mass of carbon in grams found in one molecule of the compound C7H8O4?   a.  g   b.  g   c.  g   d.  g   e. 156.000000 g   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.71 – Calculate the mass of atoms and molecules. (Example 3.3) TOPICS:   stoichiometry mass and moles of substance

 

21. Which of the following compounds contains the largest number of atoms?   a. 4.0 mol of H2S   b. 3.0 mol of NO3   c. 2.0 mol of Na2SO4   d. 5.0 mol of HBr   e. 1.0 mol of CH3COOH   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.72 – Perform calculations using the mole. TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

22. How many atoms of carbon are there in 0.37 mol of procaine, C13H20N2O2, a “pain killer” used by dentists?   a. 4.8 × 1023   b. 3.1 × 1024   c. 2.9 × 1024   d. 4.5 × 1023   e. 3.3 × 1024   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.72 – Perform calculations using the mole. TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

23. A sample of ammonium phosphate, (NH4)3PO4, contains 0.104 mol of nitrogen atoms. The number of moles of oxygen atoms in the sample is   a. 0.139 mol.   b. 0.0104 mol.   c. 0.41 mol.   d. 0.419 mol.   e. 4.6 mol.   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.72 – Perform calculations using the mole. TOPICS:   stoichiometry mass and moles of substance

 

24. A sample of thallium(III) peroxide, Tl2(O2)3, contains 2.45 mol of thallium(III) ions. The number of moles of peroxide ions in the sample is   a. 3.67 mol.   b. 1.63 mol.   c. 2.45 mol.   d. 7.35 mol.   e. 4.9361 mol.   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.72 – Perform calculations using the mole. TOPICS:   stoichiometry mass and moles of substance

 

25. Sorbose, C6H12O6, is used in making vitamin C.  A sorbose sample containing 36.0 g of carbon atoms also contains ____ g of hydrogen atoms.   a. 12   b. 6.04   c. 4.32 × 102   d. 36   e. 2.99   ANSWER:   b POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.72 – Perform calculations using the mole. TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

26. Consider the following three samples. A. A sample containing 180 g glucose (C6H12O6) B. A sample containing 90 g glucose and 90 g mannose (C6H12O6) C. A sample containing 180 g mannose Which statement is correct?   a. All three samples have the same number of oxygen atoms.   b. Both samples A and C have the same number of oxygen atoms, but more than in sample B.   c. Sample B has more oxygen atoms than sample A or sample C.   d. Sample C has more oxygen atoms than sample A or sample B   e. Sample A has more oxygen atoms than sample B or sample C.   ANSWER:   a POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.72 – Perform calculations using the mole. TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

27. Styrene’s empirical formula is CH. What mass of styrene contains 2.95 × 1021 atoms of hydrogen?  The molar mass of styrene is 104 g/mol.   a. 0.0391 g   b. 0.0636 g   c. 0.509 g   d. 0.0587 g   e. 0.00489 g   ANSWER:   b POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.73 – Convert from moles of substance to grams of substance. (Example 3.4) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

28. What is the mass of oxygen atoms in 0.380 mol Fe(CO)5?   a. 21.2 g   b. 74.4 g   c. 30.4 g   d. 6.08 g   e. 22.8 g   ANSWER:   c POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.73 – Convert from moles of substance to grams of substance. (Example 3.4) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

29. What is the mass in grams of 0.754 mol of glucose, C6H12O6?   a. 0.00419 g   b. 72.4 g   c. 136 g   d. 22.6 g   e. 239 g   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.73 – Convert from moles of substance to grams of substance. (Example 3.4) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

30. Which one of the following samples has the greatest mass?   a. 0.37 mol of camphor, C10H16O   b. 4.2 mol of ammonia, NH3   c. 9.3 mol of krypton, Kr   d. 4.0 mol of iodine vapor, I2   e. 1.6 mol of formaldehyde, CH2O   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.73 – Convert from moles of substance to grams of substance. (Example 3.4) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

31. Which of the following contains the greatest mass of oxygen atoms?   a. 0.5 mol CoSO4 • 7H2O   b. 2.1 mol KHSO4   c. 1.1 mol K2Cr2O7   d. 2.1 mol H2O2   e. 2.1 mol Na2S2O3   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.73 – Convert from moles of substance to grams of substance. (Example 3.4) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

32. Calculate the number of moles of bromine present in 20.5 mL of Br2(l), whose density is 3.12 g/mL.   a. 2.50 mol   b. 0.257 mol   c. 0.801 mol   d. 0.128 mol   e. 0.400 mol   ANSWER:   e POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.74 – Convert from grams of substance to moles of substance. (Example 3.5) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

33. How many moles of hexachlorobenzene, C6Cl6, are in 5.44 g of C6Cl6?   a. 0.0254 mol   b. 1.55 × 103 mol   c. 0.0755 mol   d. 0.019 mol   e. 0.0394 mol   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.74 – Convert from grams of substance to moles of substance. (Example 3.5) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

34. How many moles of iron atoms are contained in 4.16 g of iron?   a. 232 mol   b. 0.0548 mol   c. 0.0745 mol   d. 0.116 mol   e. 0.160 mol   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.74 – Convert from grams of substance to moles of substance. (Example 3.5) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

35. How many moles of pentane, C5H12, are contained in a 31-g sample?   a. 0.52 mol   b. 0.43 mol   c. 0.74 mol   d. 3.9 mol   e. 3.1 mol   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.74 – Convert from grams of substance to moles of substance. (Example 3.5) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

36. Sodium cyclamate, C6H11NHSO3Na, was used at one time as an artificial sweetener. C6H11NHSO3Na has a molecular mass of 201.2 g/mol. How many moles of sodium cyclamate are contained in a 56.0-g sample?   a. 0.175 mol   b. 0.160 mol   c. 0.278 mol   d. 0.255 mol   e. %1,0f mol   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.74 – Convert from grams of substance to moles of substance. (Example 3.5) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

37. How many moles of silver are contained in 7.00 kg of silver?   a. 64.9 mol   b. 64.9 × 101 mol   c. 64.9 × 10–3 mol   d. 64.9 × 103 mol   e. 64.9 × 10–1 mol   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.74 – Convert from grams of substance to moles of substance. (Example 3.5) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

38. A 0.0106-mol sample of urea, NH2CONH2, contains   a. 6.02 × 1023 molecules.   b. 2.55 × 1022 molecules.   c. 5.10 × 1022 atoms.   d. 2.55 × 1023 atoms.   e. 1.06 × 1024 atoms.   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

39. How many molecules are there in 104 g of pentylene glycol, HO(CH2)5OH?   a. 1   b. (6.02 × 1023)/104   c. 104   d. 104 × (6.02 × 1023)   e. 6.02 × 1023   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

40. How many molecules are there in 60 g of acetic acid, C2H4O2?   a. (6.02 × 1023) / 60   b. 60   c. 6.02 × 1023   d. 30   e. 60 × (6.02 × 1023)   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

41. In 0.266 mol of trimellitic acid, C6H3(COOH)3, there are   a. 1.60 × 1022 molecules.   b. 6.41 × 1024 molecules.   c. 4.80 × 1023 oxygen atoms.   d. 1.44 × 1024 carbon atoms.   e. 2.67 × 1023 hydrogen atoms.   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

42. How many molecules are there in 1.54 kg of hydrazine, N2H4?   a. 4.81 × 1023   b. 2.90 × 1025   c. 1.88 × 1022   d. 1.54 × 1026   e. 2.56 × 1021   ANSWER:   b POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

43. How many molecules are there in 2.10 mg of mannose, C6H12O6, which is a sweet-tasting sugar that has a bitter aftertaste?   a. 5.16 × 1021   b. 2.87 × 1021   c. 6.32 × 1018   d. 3.49 × 1024   e. 7.02 × 1018   ANSWER:   e POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

44. How many atoms are present in 495 g of KPF6 (MM = 184.1 g/mol)?   a. 2.38 × 1025   b. 1.62 × 1021   c. 2.69 × 1021   d. 1.21 × 1026   e. 1.29 × 1025   ANSWER:   e POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

45. Styrene’s empirical formula is CH. When it is heated to 200°C, it is converted into a polymer, polystyrene, which has excellent insulating properties. What mass of styrene contains 1.77 × 1021 molecules of styrene?  The molar mass of styrene is 104 g/mol.   a. 0.00293 g   b. 0.305 g   c. 0.587 g   d. 0.0382 g   e. 0.0235 g   ANSWER:   b POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

46. In 0.300 mol of dimethylhydrazine, (CH3)2N2H2, there are   a. 1.81 × 1024 molecules.   b. 2.51 × 1023 atoms.   c. 1.81 × 1022 molecules.   d. 2.17 × 1024 atoms.   e. 1.08 × 1024 atoms.   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

47. Which is a reasonable mass corresponding to 1026 molecules of a substance?   a. 100 ng   b. 100 g   c. 100 mg   d. 100 kg   e. 100 µg   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

48. How many aluminum atoms are there in 52 g of Al2S3?   a. 4.2 × 1023   b. 1.6 × 1021   c. 2.1 × 1023   d. 1.1 × 1021   e. 6.3 × 1023   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

49. Which one of the following contains 4.21 × 1024 atoms?   a. 91 g C2H2   b. 168 g O2   c. 56 g CH4   d. 294 g N2   e. 28 g He   ANSWER:   e POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

50. A sample of 496 g of white phosphorus, P4, contains the same number of atoms as   a. 192 g of ozone (O3).   b. 56 g of nitrogen (N2).   c. 92 g of sodium.   d. 120 g of formaldehyde (CH2O).   e. 128 g of oxygen (O2).   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

51. The total number of oxygen atoms in 1.93 g of CaCO3 (MM = 100.0 g/mol) is   a. 2.24 × 1023.   b. 4.65 × 1022.   c. 3.49 × 1022.   d. 1.92 × 1023.   e. 5.81 × 1022.   ANSWER:   c POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

52. A sample of 96 g of ozone, O3, contains the same number of atoms as   a. 96 g of oxygen (O2).   b. 8.06 g of hydrogen (H2).   c. 76 g of fluorine (F2).   d. 54 g of aluminum (Al).   e. 117 g of nickel (Ni).   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

53. Which of the following samples contains the smallest number of molecules?   a. 5.00 g of TNT, C7H5N3O6   b. 5.00 g of benzene, C6H6   c. 5.00 g of glucose, C6H12O6   d. 5.00 g of naphthalene, C10H8   e. 5.00 g of formaldehyde, CH2O   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

54. Which of the following samples contains the largest number of atoms?   a. 1 g N2   b. 1 g Be   c. 1 g Br2   d. 1 g P4   e. 1 g Si   ANSWER:   b POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

55. Which of the following samples contains the largest number of molecules?   a. 10. g Ca   b. 10. g Br2   c. 10. g Ar   d. 10. g O2   e. 10. g S8   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.2 LEARNING OBJECTIVES:   GENE.EBBI.13.75 – Calculate the number of molecules in a given mass of substance. (Example 3.6) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

56. In 1928, 1.0 g of rhenium, Re, was isolated from 660 kg of the ore molybenite. The percent by mass of this element in the molybenite was   a. 0.66 %.   b. 0.15 %.   c. 3.5 × 10–4 %.   d. 6.6 × 10–3 %.   e. 1.5 × 10–4 %.   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

57. An ore sample is found to contain 10.500000 g of cobalt and 87.3 g waste rock (gangue).  What is the percent by mass of cobalt in the ore?   a. 10.7 %   b. 12.114 %   c. 0.107 %   d. 0.12228 %   e. 1.2879 %   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas

 

58. An ore sample with a mass of 92.3 g is found to contain 17.7% by mass iron.  What mass of iron is contained in the ore?   a. 16.300000 g   b. 78.4 g   c. 1.77 g   d. 82.2 g   e. 464 g   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas

 

59. What is the percent by mass nitrogen in (NH4)2SO3?   a. 24.1 %   b. 12.961 %   c. 64.6 %   d. 39.3 %   e. 4.73 %   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas

 

60. What is the percentage by mass of chlorine in the insecticide Lindane, C6H6Cl6?   a. 20.6 %   b. 1.00 %   c. 69.6 %   d. 8.80 %   e. 73.1 %   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas

 

61. The mineral leadhillite, which is essentially Pb4(SO4)(CO3)2(OH)2 (FW = 1079 g/mol), contains ____% hydrogen by mass.   a. 76.81   b. 0.1868   c. 2.226   d. 17.79   e. 2.971   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

62. Which of the following compounds has the highest percentage of hydrogen atoms by mass?   a. CH3COOH   b. C2H5OH   c. CH3OH   d. H2CO3   e. H2C2O4   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

63. Which of the following compounds has the highest percentage of nitrogen by mass?   a. (NH4)2SO3   b. NaNO3   c. N2F4   d. NH4NO2   e. HNO3   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

64. Which of the following compounds has the same percentage of carbon and hydrogen by mass as cyclohexane, C6H12?   a. C6H14, hexane   b. C4H8, butylene   c. C6H10, cyclohexene   d. C6H6, benzene   e. C6H12O6, glucose   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

65. What is the mass percentage of carbon in the compound C6H6O3?   a. 4.8 %   b. 61.9 %   c. 57.1 %   d. 38.1 %   e. 20.0 %   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

66. What is the percentage by mass of nitrogen in ammonium phosphate, (NH4)3PO4?   a. 28.1 %   b. 14.15 %   c. 52.4 %   d. 39.9 %   e. 2.27 %   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas

 

67. A crystal of the mineral troegerite, (UO2)3(AsO4)2 • 12H2O (FM = 1304 amu), contains ____% uranium by mass.   a. 18.6   b. 47.2   c. 62.8   d. 30.0   e. 54.8   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.76 – Calculate the percentage composition of the elements in a compound. (Example 3.7) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

68. How many grams of hydrogen atoms are present in 16.4 g of water?   a. 33.1 g   b. 0.91 g   c. 1.84 g   d. 2.20 g   e. 10.9 g   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.77 – Calculate the mass of an element in a given mass of compound. (Example 3.8) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

69. How many grams of potassium are present in 28.7 g of K2Cr2O7?   a. 7.63 g   b. 1.468 g   c. 3.81 g   d. 78.2 g   e. 14.4 g   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.77 – Calculate the mass of an element in a given mass of compound. (Example 3.8) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

70. NaHCO3 is the active ingredient in baking soda. How many grams of oxygen are present in 0.25 g of NaHCO3?   a. 0.009 g   b. 0.048 g   c. 2.98 × 103 g   d. 0.016 g   e. 0.14g   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.77 – Calculate the mass of an element in a given mass of compound. (Example 3.8) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

71. Which of the following contains the greatest mass of bromine atoms?   a. 15.0 g of KBr   b. 29.0 g of Br2   c. 0.096 mol of KBr   d. 0.078 mol of Br2   e. 25.0 g of NaBrO3   ANSWER:   b POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.77 – Calculate the mass of an element in a given mass of compound. (Example 3.8) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   mass percentage OTHER:   general chemistry

 

72. The amount of calcium in a 15.0-g sample was determined by converting the calcium to calcium oxalate, CaC2O4.  The CaC2O4 weighed 10.3 g.  What is the percent of calcium in the original sample?   a. 8.8 %   b. 21.5 %   c. 12.1 %   d. 27.5 %   e. 68.7 %   ANSWER:   b POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.3 LEARNING OBJECTIVES:   GENE.EBBI.13.77 – Calculate the mass of an element in a given mass of compound. (Example 3.8) TOPICS:   stoichiometry mass and moles of substance KEYWORDS:   mole | mole calculations OTHER:   general chemistry

 

73. A compound containing only carbon, hydrogen, and oxygen is subjected to elemental analysis.  Upon complete combustion, a 0.7916-g sample of the compound produced 1.581 g of CO2 and 0.6474 g of H2O.  What is the empirical formula of the compound?   a. C3H6O3   b. C3H3O   c. C2H4O   d. C2H2O   e. CH2O3   ANSWER:   c POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.78 – Calculate the percentage of C, H, and O from combustion data. (Example 3.9) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   elemental analysis OTHER:   general chemistry

 

74. A 3.391 g sample of a compound containing only carbon, hydrogen, and oxygen is burned in an excess of dioxygen, producing 6.477 g CO2 and 3.978 g H2O.  What mass of oxygen is contained in the original sample?   a. 1.178 g   b. 1.4899 g   c. 3.086 g   d. 2.499 g   e. 0.5874 g   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.78 – Calculate the percentage of C, H, and O from combustion data. (Example 3.9) TOPICS:   stoichiometry determining chemical formulas

 

75. A 4.215 g sample of a compound containing only carbon, hydrogen, and oxygen is burned in an excess of dioxygen, producing 9.582 g CO2 and 3.922 g H2O.  What percent by mass of oxygen is contained in the original sample?   a. 27.54 %   b. 32.75 %   c. 12.73 %   d. 13.42 %   e. 6.939 %   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.79 – Calculate the percentage of C, H, and O from combustion data. TOPICS:   stoichiometry determining chemical formulas

 

76. A 4.957 g sample of a hydrocarbon is burned in an excess of dioxygen, producing 9.284 g CO2 and water.  What mass of hydrogen is contained in the original sample?   a. 2.423 g   b. 4.327 g   c. 14.24 g   d. 1.794 g   e. 2.478 g   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.78 – Calculate the percentage of C, H, and O from combustion data. (Example 3.9) TOPICS:   stoichiometry determining chemical formulas

 

77. A 3.903 g sample of a hydrocarbon is burned in an excess of dioxygen, producing 7.31177 g CO2 and 4.488 g H2O.  What is the empirical formula of the hydrocarbon?   a. CH3   b. CH2   c. C2H3   d. CH4   e. CH   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.80 – Determine the empirical formula of a binary compound. TOPICS:   stoichiometry determining chemical formulas

 

78. A 0.4647-g sample of a compound known to contain only carbon, hydrogen, and oxygen was burned in dioxygen to yield 0.01962 mol of CO2 and 0.01961 mol of H2O. What is the empirical formula of the compound?   a. CHO   b. C3H3O2   c. C2H2O   d. C3H6O2   e. C6H3O2   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.78 – Calculate the percentage of C, H, and O from combustion data. (Example 3.9) TOPICS:   stoichiometry determining chemical formulas

 

79. A sample containing only carbon, hydrogen, phosphorus, and oxygen is subjected to elemental analysis.  After complete combustion, a 0.3584-g sample of the compound yields 0.5139 g of CO2, 0.3155 g of H2O, and 0.2762 g of P4O10.  What is the empirical formula of the compound?   a. CH3PO   b. C2H3PO   c. C2H6P2O4   d. C3H9PO   e. CH2P4O13   ANSWER:   d POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.78 – Calculate the percentage of C, H, and O from combustion data. (Example 3.9) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   elemental analysis OTHER:   general chemistry

 

80. A sample containing only carbon, hydrogen, and silicon is subjected to elemental analysis.  After complete combustion, a 0.7020-g sample of the compound yields 1.4 g of CO2, 0.86 g of H2O, and 0.478 g of SiO2.  What is the empirical formula of the compound?   a. CH3Si   b. C2H4Si   c. C4H12Si   d. C6H12Si2   e. CH2Si   ANSWER:   c POINTS:   1 DIFFICULTY:   difficult REFERENCES:   3.4 LEARNING OBJECTIVES:   GENE.EBBI.13.78 – Calculate the percentage of C, H, and O from combustion data. (Example 3.9) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   elemental analysis OTHER:   general chemistry

 

81. Of the following, the only empirical formula is   a. C4H10.   b. C4H8.   c. C5H14.   d. H2O2.   e. O3.   ANSWER:   c POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.81 – Define empirical formula. TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

82. Which of the following is the empirical formula for the molecule below?   a. CHO   b. CH3COOH   c. C2H4O2   d. CH2O   e. none of the above.   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.81 – Define empirical formula. TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

83. Analysis of a compound showed that it contained 76.0 % fluorine atoms and 24.0 % carbon atoms by mass. What is its empirical formula?   a. CF2   b. C2F3   c. CF3   d. C2F5   e. CF   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.82 – Determine the empirical formula of a binary compound from the masses of its elements. (Example 3.10) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

84. A sample of an oxide of antimony (Sb) contained 48.5 g of antimony combined with 15.9 g of oxygen. What is the simplest formula for the oxide?   a. SbO2   b. SbO   c. Sb2O3   d. Sb3O   e. Sb2O5   ANSWER:   e POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.82 – Determine the empirical formula of a binary compound from the masses of its elements. (Example 3.10) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

85. Chlorine was passed over 1.41 g of heated titanium, and 4.54 g of a chloride-containing compound of Ti was obtained. What is the empirical formula of the chloride-containing compound?   a. TiCl2   b. TiCl4   c. TiCl   d. TiCl3   e. Ti2Cl3   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.82 – Determine the empirical formula of a binary compound from the masses of its elements. (Example 3.10) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

86. A 4.94-g sample of an oxide of chromium contains 3.06 g of chromium. Calculate the simplest formula for the compound.   a. CrO5   b. Cr2O   c. CrO2   d. CrO   e. Cr2O3   ANSWER:   c POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.82 – Determine the empirical formula of a binary compound from the masses of its elements. (Example 3.10) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

87. A compound is composed of only C and H. It contains 92.26 % C. What is its empirical formula?   a. C2H5   b. C2H3   c. C3H4   d. CH   e. CH2   ANSWER:   d POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

88. A compound composed of only C and H contains 79.88 % C by mass.  What is its empirical formula?   a. CH3   b. CH   c. C2H   d. CH4   e. CH2   ANSWER:   a POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

89. A hydrocarbon, subjected to elemental analysis, was found to contain 79.89 % carbon and 20.11 % hydrogen by mass.  What is the empirical formula of the hydrocarbon?   a. CH4   b. C2H6   c. C4H   d. C10H   e. CH3   ANSWER:   e POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

90. A particular compound contains, by mass, 25.5 % carbon, 40.4 % fluorine, and 34.1 % oxygen.  A 0.050-mol sample of this compound weighs 5.80 g.  The molecular formula of this compound is   a. C2F2O2.   b. C3F3O.   c. CFO.   d. C4F4O4.   e. C5F5O5.   ANSWER:   d POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   molecular formula OTHER:   general chemistry

 

91. What is the empirical formula of an oxide of nitrogen that contains 25.93 % nitrogen by mass?   a. NO2   b. N2O   c. N2O3   d. NO   e. N2O5   ANSWER:   e POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

92. The analysis of an organic compound showed that it contained 0.630 mol of C, 0.0300 mol of H, 0.420 mol of O, and 0.210 mol of N. How many nitrogen atoms are there in the empirical formula for this compound?   a. 10   b. 7   c. 2   d. 4   e. 3   ANSWER:   b POINTS:   1 DIFFICULTY:   easy REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

93. A sample containing 0.400 mol of a compound is composed of 2.41 × 1023 atoms of sodium, 14.19 g of chlorine atoms, and 19.22 g of oxygen atoms. The formula of the compound is   a. NaClO3.   b. NaClO5.   c. NaClO.   d. NaClO4.   e. NaClO2.   ANSWER:   a POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   empirical formula OTHER:   general chemistry

 

94. The analysis of an organic compound showed that it contained 0.105 mol of C, 0.315 mol of H, and 0.0350 mol of N. Its molecular mass is 59 amu. How many atoms of carbon are there in the empirical formula for the compound, and how many are in the molecular formula?   a. empirical = 2, molecular = 3   b. empirical = 3, molecular = 9   c. empirical = 3, molecular = 3   d. empirical = 2, molecular = 4   e. empirical = 5, molecular = 10   ANSWER:   c POINTS:   1 DIFFICULTY:   moderate REFERENCES:   3.5 LEARNING OBJECTIVES:   GENE.EBBI.13.83 – Determine the empirical formula from the percentage composition. (Example 3.11) TOPICS:   stoichiometry determining chemical formulas KEYWORDS:   molecular formula OTHER:   general chemistry