Chemistry Unit 8 Practice Test
States of Matter and Gas Laws
No work shown = no credit. Please write legibly. Numerical answers must be rounded to
the appropriate number of significant figures or decimal points and must contain the
appropriate unit. Answers with the incorrect number of significant figures will lose ¼
credit. Answers with no units or the wrong units will lose ½ credit.
1.
Tell whether each of the following states of matter has a definite shape (1 point), a
definite volume (1 point), and is compressible (1 point). (9 points total).
(A) Solid
Definite shape (yes/no)?
_yes_
Definite volume (yes/no)?
_yes_
Compressible (yes/no)?
_no__
Definite shape (yes/no)?
_no__
Definite volume (yes/no)?
_yes_
Compressible (yes/no)?
_no__
Definite shape (yes/no)?
_no__
Definite volume (yes/no)?
_no__
Compressible (yes/no)?
_yes_
(B) Liquid
(C) Gas
2.
Name each of the labeled phase changes in the diagram below. Each item is worth 1
point (6 points).
gas
(A)
(D)
(B)
(C)
(A)
(B)
(C)
(D)
(E)
(F)
sublimation
deposition
vaporization
condensation
melting
freezing
(E)
solid
liquid
(F)
3. What is STP? (You need to give values as well as a definition.) (5 points)
STP stands for “standard temperature and pressure”. Standard temperature is 273 K (also
acceptable: 0ºC or 32º F). Standard pressure is 1 atm (or 760 mmHg or 101.325 kPa)
4. Convert the following temperatures to Kelvins. Show your work!!! Record your
answers with three significant figures. Each item is worth 2.5 points (5 points).
(A) 35º C
___308 K__
35º C + 273 = 308 K
(B) -144º F
___175 K__
(-144º F – 32) / 1.8 = -97.8º C
-97.8º C + 273 = 175 K
5. Convert the following pressures to atmospheres. Show your work!!! Record your
answers with three significant figures. Each item is worth 2.5 points (5 points).
(A) 195 kPa
195 kPa x
_1.92 atm__
1 atm
= 1.92 atm
101.325 kPa
(B) 559 mmHg
559 mmHg x
_0.736 atm_
1 atm
= 0.736 atm
760 mmHg
6. Use the phase diagram for
water shown at right to
answer the following
questions. Each item is
worth 2 points (10 points).
(A) What is the phase of water
under 1 atm of pressure
and at -15º C?
solid
(B) What is the phase of water
under 1 atm of pressure
and at 200º C?
gas
(C) What is the phase of water
under 1 atm of pressure
and at 25º C?
liquid
(D) At what temperature and pressure does water exist simultaneously in all three phases?
0.00988º C and 6.0x10-3 atm
(E) If you have a sample of liquid water under 1 atm of pressure and at 50º C, what are two
ways you could cause that water to start boiling?
Raise the temperature or lower the pressure.
7. Solve the following problems. Pay attention to significant figures and units. Show all
work!!! Each item is worth 5 points (15 points).
(A) What volume does 4.00 moles of an ideal gas occupy when the temperature is 400. K
and the pressure is 1.25 atm?
PV = nRT
(1.25 atm) V = (4.00 mol)(0.0821
L * atm
)(400. K)
mol * K
(1.25 atm) V = 131 L*atm
V = 105 L
(B) At what pressure does 20.0 grams of oxygen gas, O 2 occupy a volume of 18.0 Liters
when the temperature is 290. K? Assume ideal behavior.
First convert 20.0 grams into moles:
20.0 g O2 x
1 mol O 2
= 0.625 mol O2
32.00 g O 2
PV = nRT
P (18.0 L) = (0.625 mol)(0.0821
L * atm
)(290. K)
mol * K
P (18.0 L) = 14.9 L*atm
P = 0.827 atm
(C) At what temperature (in ºC) does 4.10 moles of an ideal gas occupy a volume of 100. L
when the pressure is 850. mmHg?
First convert the pressure to atmospheres:
850. mmHg x
1 atm
= 1.12 atm
760 mmHg
PV = nRT
(1.12 atm)(100. L) = (4.10 mol)(0.0821
112 atm*L = (0.337
T = 332 K
T = 59º C
L * atm
)T
K
L * atm
)T
mol * K
8. What is the density of methane, CH4, at STP? Pay attention to significant figures and
units. Show your work!!! (10 points).
Molar mass of CH4:
1 x carbon =
4 x hydrogen =
Total =
D=
D=
12.01 g/mol
4.04 g/mol
16.05 g/mol
PM
RT
(1.00 atm)(16.05 g/mol)
= 0.716 g/L
L * atm 

 0.0821
(273K)
mol * K 

9. Solve the following problems. Pay attention to significant figures and units. Show all
work!!! Each item is worth 5 points (10 points).
(A) What is the volume of 6.00 moles of carbon dioxide gas at STP?
1 mole of any gas at STP = 22.4 L
6.00 mol x
22.4 L
= 134 L
1 mol
(B) How many moles of neon are in 5.6 Liters at STP?
5.6 L x
1 mol
= 0.25 mol
22.4 L
10. A gas sample has a volume of 40.0 Liters at STP. What is its volume when the
temperature is raised to 315 K and the pressure is lowered to 0.800 atm? Pay attention
to significant figures and units. Show all work!!! (10 points)
P1V1 P2 V2

T1
T2
(1.00 atm)(40.0 L) (0.800 atm)V 2

273 K
315 K
0.147
atm 
atm * L 
=  0.00254
 V2
K 
K

V2 = 57.9 L
11. A gas sample occupies a volume of 99.5 L when its temperature is 290. K. If the
pressure remains constant, what volume will the gas occupy when the temperature
decreases to 245 K? Pay attention to significant figures and units. Show all work!!! (10
points)
At constant pressure,
V1 V2

T1 T2
V2
99.5 L

290. K 245 K
0.343
V2
L
=
K 245 K
V2 = 84.1 L
12. A sample of hydrogen gas is collected over water. The total pressure inside the
collection bottle is 766 mmHg. If the water vapor pressure is 24 mmHg, what is the
pressure of the hydrogen gas alone? Pay attention to significant figures and units.
Show all work!!! (5 points)
Ptotal = Phydrogen + Pwater vapor
766 mmHg = Phydrogen + 24 mmHg
Phydrogen = 742 mmHg