A. Determining Molar Masses (Show All Work)

Chemistry Name :

Worksheet : Ch. 10 : Obj. 6-9 #3 Date :

A. Determining molar masses (show all work):

e.g. gram formula mass of sodium oxide (Na2O = 2 x 22.99 + 16.00 = 61.98 g)

1. Determine the gram formula masses (masses of a single mole)of the following ionic compounds.

a. aluminum oxide :

b. lithium sulfate :

c. calcium hydroxide :

d. zinc chloride :

2. Determine the gram molecular masses (masses of a single mole)of the following molecular (covalently bonded) compounds.

a. Ozone (O3) :

b. glucose (C6H12O6)

c. diphosphorus pentaoxide :

B. Mole - particle conversions :

3. One mole equals 6.02 x 1023 representative particles (atoms, molecules or ions)of a substance. How many atoms are there in 8.00 moles of carbon?

4. How many moles of diphosphorus pentaoxide are there in 2.88 x 1031 molecules of diphosphorus pentaoxide?

C. Mole - mass conversions :

5. How many moles are there in 22.005 grams of carbon?

6. How many moles are there in 50.122 g of calcium?

7. How many moles are there in 500.00 grams of zinc?

8. What is the mass of 4.00 moles of carbon disulfide?

9. How many moles are there in 450.00 grams of lithium hydroxide?

10. How many grams are there in 4.50 moles of lithium hydroxide?

C. More complex problems :

11. How many moles of fluorine are there in 12.20 grams of xenon tetrafluoride?

12. How many hydrogen atoms are there in 5.00 moles of methane (CH4).

13. How many atoms of carbon are there in 9.00 mol of glucose(C6H12O6)?

14. How many hydrogen atoms are there in 85.0 grams of acetylene (C2H2)?

15. How many grams of carbon are there in 200.05 moles of octane(C8H18)?

_____ 16. Avogadro’s number represents the number of atoms in

(a) 12g of C-12

(b) 320g of sulfur

(d) 12.7g of iodine

_____ 17. The number of moles of oxygen atoms in 6.02 × 1024 CO molecules is

(a) 1

(b) 0.5

(d) 10

_____ 18. Number of electrons in 1.802 g of H2O is:

(a) 6.02 x 1023

(b) 3.011 x 1023

(d) 6.02 x 1024

_____ 19. A sample of phosphrous trichloride contains 1.4 moles of the substance. How many atoms are there is the sample?

(a) 5.6

(b) 4

(d)3.372× 1024

_____ 20. Which of the following contains greatest no. of molecules?

(a) 170 g NH3

(b) 280 g N3

(d) 600.0 O2

_____ 21. Which of the following contains the greatest mass?

(a) 2.0 mol NH3

(b) 6.02 x 1024 molec.NH3

(d) 2.0 mol N2H4

_____ 22. Which of the following has the largest number of atoms ?

(a) 0.5mol Cu

(b) 0.635 g Cu

(c ) 0.25 mole of Cu

(d) 3.35 × 1020 amu of Cu

_____23. Which of the following has maximum mass?

(a) 0.10 mol C

(b) 0.1 mol NH3

(d) 0.010 mol carbon dioxide.

_____ 24. Total number of atoms present 17.04 g of NH3 is

(a) 6.02 × 1023

(b) 2 × 6.02 × 1023

(d) 4 × 6. 02 ×1023

_____ 25. The number of atoms present in 16 g of oxygen(O2) is

(a) 6.05 × 1011.5

(b) 3.01 × 1023

(d) 6.02 × 1023

Answers : 1a. 101.96 g/mol 1c. 74.10 g/mol 2a. 48.00 g/mol 3. 4.82 x 1024 atoms C 4. 4.78 x 107 mol 5. 1.832 mol C 6. 1.251 mol Ca 7. 7.646 mol Zn 8. 305 g CS2 9. 18.79 mol LiOH 10. 108 g LiOH 11. 0.2355 mol F 12. 1.20 x 1025 atoms H 13. 3.25 x 1025 atoms C 14. 3.93 x 1024 at H 15. 19220 g C