conversion-method-moles-and-atoms

1. Write out conversion factors between the moles of each element and the moles of the compound C5H12

2. Write out the conversion factor of the given element in the given compound using the mass percent composition

a) Carbon dioxide is 27.19% carbon by mass

b) Butane is 17.34% hydrogen by mass

c) C6H8O7 is 58.29% oxygen by mass

The Mole Concept

3. How many moles of atoms are in the following?

a) 8.22 x 1024 As atoms

b) 4.41 x 1022 Ne atoms

c) 6.77 x 1023 Li atoms

d) 2.10 x 1021 S atoms

4. How many atoms are in the following given numbers of moles of an element?

a) 0.994 mol F

b) 4.39 mol Sr

c) 9.1 x 10-3 mol B

d) 13.8 mol Cl

5. Complete the table:

6. Calculate the mass in grams of the following:

a) 4.45 x 1019 Ag atoms

b) 5.50 x 1024 Bi atoms

c) 2.08 x 1021 Se atoms

d) 7.31 x 1024 Ar atoms

7. Calculate the number of atoms in each of the following:

a) 14.8g Al

b) 3.98g Ca

c) 1.90g Co

d) 26.7g S

8. Complete the table:

9. Calculate the mass of the following in grams:

a) 6.10 mol carbon monoxide

b) 0.364 mol sulfur hexafluoride

c) 4.44 mol potassium hydroxide

d) 1.71 mol lithium nitrate

10. Complete the table:

11. Calculate the number of molecules of the following:

a) 13.2g SO2

b) 9.03g CH4

c) 0.00888g H2

d) 157g LiBr

12. A sample of C6H6 has a mass of 15ng. Calculate the number of formula units.

Chemical Formulas as Conversion Factors

13. Calculate the number of moles of O in the following:

a) 11.4 mol CO2

b) 0.761 mol H2O

c) 4.08 mol N2O5

d) 0.302 mol HNO3

14. How many moles of H are in 1.85 mol [Cr(OH2)5Cl] Cl•H2O?

15. Calculate the mass in kg of the following which each contain 3.5 x 102 kg of lithium.

a) Li2SO4

b) LiOH

c) LiBr

16. Which of the following contains the greatest number of moles of oxygen? Show all work.

a) 3.03 mol C2H6O2

b) 16.9 mol N2O3

c) 8.27 mol Sr(NO3)2

d) 0.0180 mol BaSO4

Mass Percent Composition

17. A 8.91g sample of an organic compound is found to contain 3.34g C, 0.98g H, 2.61g O, and 1.98g N. Determine the mass percent of each element.

18. BaSO4 is approximately 58.84% barium by mass. Calculate the mass of barium in grams in a 7.22g sample of BaSO4.

19. Calculate the mass percent composition of oxygen in the following compounds.

a) CrO3

b) SO2

c) NaOH

d) Al2(SO4)3

20. Calculate the mass percent composition of all the individual elements in each of the following compounds.

a) HClO3

b) AgBr

c) PbSO4

d) CH4

Calculating Empirical Formulas

21. An organic compound is found to have 36.03g of carbon, 6.048g hydrogen, and 16.00g oxygen. Determine the empirical formula of the organic compound.

22. The nonsteroidal anti-inflammatory drug Ibuprofen consists of 75.69% carbon, 8.80% hydrogen, and 15.51% oxygen. Determine the empirical formula of ibuprofen.

Calculating Molecular Formulas

23. Determine the molecular formula of each of the following using the given empirical formulas and total molar masses.

a) CO2H, 225.09g/mol

b) CClN, 184.41g/mol

c) C2H3O, 86.09g/mol

d) C4H8O, 144.21g/mol

Challenge Problems

24. How many ethanol molecules are in a 613mL container of pure ethanol? Ethanol has a density of 0.7893 g/cm3.

25. Aldrin is an insecticide that was commonly used in soil fields until it was banned in many counties. It is found to consist of 39.50% carbon, 2.21% hydrogen, and 58.29% chlorine. Its molar mass is 364.884g/mol. Using this information, determine the molecular formula of Aldrin.

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