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Chapter 7 Problems

1. To what kinds of substances does the term formula mass refer?
     

2. Calculate the formula mass for each of the following compounds:

3. Find the percent composition of each element in the following
       compounds:

4. Give the empirical formula for each

5. Write formulas for the following hydrates

6. Explain the difference between atomic mass and average atomic mass.
   

7. How is Avagadro's number 6.023 x 10²³ related to moles?
   

8. Which of the following has the greater number of molecules, 10 g of N₂ or 10 g of O₂? Explain.
   

 9. What information does the percent composition reveal about a compound?
   

10. Compare the molecular, empirical, and structural formulas of a compound.
   

    The following questions need to be worked out on paper so that I can see your work.

11. How many molecules are there in 2.00 moles of sucrose, C₁₂H₂₂O₁₁?

12. How many atoms are there in 1.25 x 10^-2 mol of mercury?

13. How many formula units are there in 3.12 moles of MgCl₂?

14. How many moles are the re in 2.50 x 10²⁵ formula units of MgO?

15. How many moles are there in 7.51 x 10²⁴ molecules of benzene, C₆H₆?

16. How many moles are there in 3.6 x 10²³ molecules of oxygen gas, O₂?

17. How many grams are there in 1.204 x 10²⁰ atoms of phosphorus?

18. How many grams are in 2.7 moles of table salt, NaCl?

19. How many atoms of gold are there in 10.6g of gold?

20. How many moles of sodium nitrate are there in a beaker that contains 0.500 kg of sodium
    nitrate?

21. A compound is analyzed and found to contain 63.50% Ag, 8.25% N, and 28.25% O. Calculate
    the empirical formula.

22. A 1.344 g sample of a compound contains 0.365 g Na, 0.221 g N, and 0.758 g O. What is the
    percent composition and empirical formula for this compound?

Just For Fun

    Name the movie that the following sound clip comes from: click here