1. Counting: Example, counting sheep
#47 Give three common ways that matter
is measured. Give examples of each
Counting: Example, counting sheep
Volume: Example: estimating the #
of jelly beans in a large jar.
Mass: Example: Weighing out some
NaCl.

2. #48 Name the representative particle
of each substance:
a. oxygen gas O2 (a molecule)
b. sodium sulfide Na2S (a formula unit)
c. sulfur dioxide SO2 (a molecule)
d. potassium K (an atom)

3. #49 How many hydrogen atoms are in a representative particle of each
substance?
a. Al(OH)
b. H2C2O
c. (NH4)2HPO4 9
d. C4H10O

4. They all contain exactly the same: 6.02 x 1023 molecules
#50 Which contains more molecules:
1.00 mole H2O2 , mole of C2H6,
or 1.00 mole CO?
They all contain exactly the same:
6.02 x 1023 molecules

5. Since H2O2 contains 4 atoms per molecule, C2H6 contains 8 atoms
#51 Which contains more atoms:
1.00 mole of H2O2 ,
1.00 mole of C2H6,
or 1.00 mole of CO?
Since H2O2 contains 4 atoms per
molecule, C2H6 contains 8 atoms
per molecule, and CO only 2 atoms
per molecule;
1 mole of C2H6 contains the
most atoms (6.02 x 1023 times 8)

6. #52 Find the number of represent- ative particles in each substance:
a moles Sn = (6.02 x 1023 times 3)
b moles KCl = (6.02 x 1023 times .4)
c moles SO2 = (6.02 x 1023 times 7.5)
d x 10-3 moles NaI =
(6.02 x 1023 times .0048)

7. #53 Calculate the molar mass
of each substance:
a. H3PO4 = g/mole
b. N2O3 = g/mole
c. CaCO3 = g/mole
d. (NH4)2SO4 = g/mole
e. C4H9O2 = g/mole
f. Br2 = g/mole

8. #54 Calculate the mass of 1.00 mole
of each of these substances
the mass on one mole of something
is just its molar mass…
a. SiO2 = g/mole
b. N = g/mole
c. Fe(OH)3 = g/mole
d. Cu = g/mole

9. a. 15.5 g SiO2 15.5 g x 1 mole (28.1 + 32) = .258 moles
#58 How many moles is each of the
following:
In each of these you simply divide by the
molar mass of each compound
a g SiO g x 1 mole
( )
= moles
b g AgCl x10-4 moles

10. c g Cl mole
d g KOH mole
e. 937 g Ca(C2H3O2) mole
f g Ca mole

11. #59 Find the mass of each substance.
In each of these you multiply by the
molar mass
a mole C5H12 = 108 grams
b mole F2 = 547 grams
c mole Ca(CN)2 = 71.8 grams
d mole H2O2 = 238 grams
e. 5.6 mole NaOH = 224 grams
f x 10-2 mole Ni = 1.88 grams

12. The volume of any gas at STP is 22.4 liters per mole
#60 Calculate the volume of each of the
following gases at STP.
The volume of any gas at STP is
22.4 liters per mole
x 22.4 liters = 1.7 x 102 liter
1 mole
a. 7.6 moles Ar
x 22.4 liters = 9.9 liter
1 mole
b moles C2H6

13. 44 g x 1 mole = 1.96 g 1 mole 22.4 liters liter 20.2 g
#61 What is the density of each of the
following gases at STP.
(density is in units of grams/liter)
a. C3H8 The molar mass is: (12x3 +8) = 44
44 g
1 mole
x 1 mole = g
22.4 liters liter
b. Ne
The molar mass is: 20.2
20.2 g
1 mole
x 1 mole = g
22.4 liters liter

14. 46 g x 1 mole = 2.05 g 1 mole 22.4 liters liter
#61 What is the density of each of the
following gases at STP.
(density is in units of grams/liter)
c. NO2 The molar mass is: (14+32) = 46
46 g
1 mole
x 1 mole = g
22.4 liters liter

15. #62 Find each of the following
quantities:
a. the volume, in liters, of 835 g SO3
835 g x 1 mole x
22.4 liters =
1 mole
234 Liters SO3

16. #62 Find each of the following
quantities:
b. the mass in grams, of a molecule
of aspirin (C9H8O4)
1 molecule x mole x
x 1023 molecules
180 g = x grams
1 mole
22.4 liters =
1 mole

17. #62 Find each of the following quantities:
c. The number of atoms in 5.78 moles
NH4NO3
5.78 moles x x1023 molecules
mole
9 atoms = x 1025 atoms
1 molecule NH4NO3

18. #63 Calculate the percent composition
of each compound.
a. H2S
The total is: (1.0 x 2) = 34.1
% comp. H is: x 100 = 5.9%
34.1
% comp. S is: x 100 = 94.1%
34.1

19. #63 Calculate the percent composition of each compound. b. (NH4)2C2O4
The total is:
(18.0 x 2)
= 124.0
% comp. N is: x 100 = 22.6%
124.0
% comp. H is: x 100 = 6.5%
124.0
% comp. C is: x 100 = 19.4%
124.0
% comp. O is: x 100 = 51.6%
124.0

20. #63 Calculate the percent composition of each compound. c. Mg(OH)2
The total is:
24.3 +(17.0 x 2)
= 82.6
% comp. Mg is: x 100 = 41.7%
82.6
% comp. O is: x 100 = 54.9%
82.6
% comp. H is: x 100 = 3.4%
82.6

21. #63 Calculate the percent composition of each compound. d. Na3PO4
The total is:
(23.0 x 3)
= 164.0
% comp. Na is: x 100 = 42.1%
164.0
% comp. P is: x 100 = 18.9%
164.0
% comp. O is: x 100 = 39.0%
164.0