I. Multiple
Choice Questions - Choose the best answer for each question.
1.) A
15.0 liter gas sample is heated from 29 oC
to 67 oC at constant pressure conditions.
Under these conditions, which of the following
statements is correct?
(A) the
number of moles of gas increases
(B) the
number of moles of gas decreases
(C) the
volume decreases
(D) the volume increases
(E)
none of the above are correct
2.) A
sample of CO2 gas occupies 3.0 L at 35 oC
and 1.0 atm. What is the new volume if
the temperature and pressure are changed to 48 oC and 1.5 atm?
(A) 3.0
L (B) 1.9
L (C) 4.7
L (D) 4.3
L (E) 2.1 L
3.)
If 10.7 liters of a gas at 35.0 oC
has its temperature increased to 50.0 oC,
what is the
new volume?
(A) 7.3
L (B) 10.2
L (C) 11.2 L
(D) 15.9 L
4.) In
the ideal gas equation, the ideal gas constant (R) is equal to
(A) n T
(B) P V
(C) P V T (D)
n (E)
V T
P
V
n T
n
P V T
n P
5.)
Boyle's Law relates pressure and volume. What is the equation for Boyle's
Law?
(A) P1 V1 = P2 V2
(B) P1 = P2
(C) P1 + V1
= (D) P V = n R T
V1 V2
P2 + V2
6.)
If 0.50 moles of helium are placed inside a 1.50 L container at 77 K, what is
the pressure
exerted by the helium gas?
(A) 0.48 atm
(B) 1.2 atm
(C) 2.1 atm
(D) 3.7 atm
(E) 4.5 atm
7.)
In order to solve a problem using the ideal gas equation, how many values must
be given
to solve the problem?
(A)
1 (B)
2 (C) 3
(D) 4 (E) 5
8.)
Which of the following is/are constant in the equation for Boyle's Law?
(I)
Pressure (II)
Volume (III)
Moles (IV)
Temperature
(A) I
only
(B) II and III only
(C) I and IV only
(D) I, II,
and IV only (E) III and IV only
9.)
If a gas at 2.9 atm and 34 oC
has its pressure decreased to 2.4 atm, what is the
new
temperature of the gas?
(A) 147
K (B) 254 K
(C) 147 oC
(D) 254 oC
(E) 28 oC
10.)
How do you convert from degrees Celsius to Kelvins?
(A) add
100 (B)
subtract 173
(C) subtract 273
(D) subtract
100 (E) add 273
11.)
The quantity of a gas is measured in
(A) Kelvins
(B) Liters
(C)
Atmospheres (D) Moles
12.)
The average kinetic energy of the molecules of a gas is determined by the __ of
the gas.
(A) quantity
(B) mass (C)
pressure
(D) temperature
(E) volume
II. Solve each of the following problems. (You must
show your work!)
1.) A
5.00 liter container is filled with N2 gas at a pressure of 3.00 atm and 250 oC.
What
is the volume of the container that is used to
hold the same gas at STP (standard
temperature and pressure)?
P1 V1 = P2 V2
(3.00
atm) (5.00 L) = (1.00 atm)
(V2)
T1 T2
(523
K)
(273 K)
4095 = 523 (V2)
V2 = 7.83 L
2.)
What volume of N2 gas at 0.947 atm and 23 oC is required to react with 7.35 liters of H2
gas at the same temperature and
pressure? N2 + 3
H2 --> 2
NH3
? L 7.35 L
(1.)
Find moles of given.
P V = n R T
(0.947 atm) (7.35 L) = n (0.0821 L
atm/mole K) (296 K)
24.3016 n = 6.96045
n = .286 moles H2
(2.) Use
mole ratio.
2.86 moles H2 = x moles N2
3
1
3 x = 0.286
x = 0.0953 moles N2
(3.) Find
answer.
P V = n R T
(0.947 atm) V = (0.0953 moles)
(0.0821 L atm/mole K) (296 K)
0.947 V = 2.316
V = 2.45 L of H2 required
3.)
How many liters of O2 gas at STP are evolved when 3.25 grams of KNO3
decomposes to
KNO2 and O2?
2 KNO3
--> >2 KNO2
+ O2
(1.) Find
moles of given.
3.25 g KNO3 = 0.0321 moles KNO3
101.1 g/mole
(2.) Use mole
ratio.
0.0321 moles KNO3 = x moles O2
2
1
2 x = 0.0321
x = 0.01605 moles O2
(3.) Find answer.
(1.00 atm) V = (0.01605 moles)
(0.0821 L atm/mole K) (273 K)
V = 0.360 L
4.)
What is the volume of 0.55 moles of an ideal gas that is at 1.03 atm and 94 oC?
P V = n R T
(1.03 atm) V = (0.55 moles)
(0.0821 L atm/mole K) (367 K)
V = 16
L
5.)
If a gas has an initial pressure of 1.45 atm and an
initial volume of 23.0 liters, what is its
final volume if the pressure is increased to
2.43 atm?
P1 V1 = P2 V2
(1.45 atm) (23.0 L) = (2.43 atm) V2
V2
= 13.7 L
6.) a.) In an experiment, a student is to determine
the molar mass of an unknown gas.
During the experiment,
the student measures the following data:
The mass of
the gas is 0.65 grams. The pressure is 1.07 atm. The volume is
350 mL. The temperature is 21.5 oC.
What is the molar mass of the gas?
MM = mass R T
MM = (0.65 g) (0.0821 L atm/mole K)
(294.5 K)
P
V
(1.07 atm) ( 0.350 L)
MM = 42 g/mole
b.) Later, it is revealed that the unknown gas is
propane (C3H8). What is the student's
percent
error?
C: 3 x 12 =
36
(44 - 42) x 100 = 4.5 %
H: 8 x 1 = 8
44
44
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