1.
Project in Chemistry
SY: 2012-2013
Submitted by: Axl Merk Mindajao
Mary Rose Baccay
III-OBB
Submitted to: Mrs. Panlasiqui
2.
Recall
1. If the pressure exerted on a gas is
tripled, what will happen to the volume
(assuming the temperature and amount
of gas remains constant)?
A. x2 C. x 1/2
B. X3 D. x 1/3
3.
2. Carbon dioxide occupies a 2.54 L
container at STP. What will be the
volume when the pressure is 150
KPa and 26 C?
A. 1.89 L C. 0.163 L
B. 42300 L D. 14.1 L
4.
3. In which of the following sets of conditions
would a gas most act as a real gas?
A. high temperature and low pressure
B. high temperature and high pressure
C. low temperature and high pressure
D. low temperature and low pressure
5.
4. Which of the following terms is
used to describe the average kinetic
energy of the molecules in a
sample?
A. manometer C. pressure
B. temperature D. volume
6.
5. Which of the following is not a
standard pressure
measurement?
A. 101.3 kPa C. 760 mm Hg
B. 1 atm D. 273 K
7.
6. The volume of a gas is increased
from 150.0 mL to 350.0 mL by
heating it. If the original
temperature of the gas was 25.0 °C,
what is the final temperature?
A. -146 °C C. 695 °C
B. 10.7 °C D. 150 °C
8.
7. What is the name of the phase
change that exists when a solid
turns into a liquid?
A. depositon C. sublimation
B. melting D. freezing
9.
8. A balloon is inflated to a volume of
130 ml at a pressure of 690 mmHg. If
the pressure is increased to 1000
mmHg, what will the new volume be?
A. 188 ml C. 89.7 ml
B. 98.8 ml D. 40300 ml
10.
9. What type of relationship is shown
between temperature and
pressure?
A. direct C. exponential
B. inverse D. logarithmic
11.
10. How many mm Hg is equal to 121
kPa?
A. 1.19 C. 636
B. 16.1 D. 908
12.
Answers
1.d 6. c
2.a 7. b
3.c 8. c
4.b 9. a
5.d 10. d
14.
Objectives
To demonstrate the ability to use
Dalton’s Law of Partial Pressure in
calculations.
To calculate the total pressure of a
mixture of gases or the partial pressure
of a gas in a mixture of gases.
To employ Dalton’s Law of Partial
Pressure to predict the pressure of a gas
mixture.
15.
Unlocking of Words
• Pressure- the force exerted by gas
particles that hit the walls of a container;
a force applied per unit area.
• Partial pressure- the individual pressure
of each gas in a mixture.
• Water vapor- gaseous water found in the
air that is below the boiling point of
water.
16.
Lesson
• The English chemist John Dalton
investigated pressures in mixture of
gases. Dalton’s Law of Partial Pressure
states that: “At constant volume and
temperature, the total pressure in a
mixture of gases is equal to the sum
of the partial pressures of the
component gases.”
17.
• In equation form, PT=P1+P2+....
where
PT= total pressure
P1= partial pressure of gas 1
P2= partial pressure of gas 2
18.
Activity
Problem 1: Oxygen gas occupies
500 ml at 20°C and 760 mmHg.
What volume will it occupy if it
is collected over water at 30°C
and 750 mmHg? (Water vapor
pressure at 30°C 31.8 mmHg)
20.
Step 2: The combined gas formula
P1V1= P2V2 V2= P1 T2
T1 T2 P2 T1
Step 3:
V2= 500 ml 760 mmHg 303 K
718.2 mmHg 93 K
V2= 547 ml
21.
Problem 2: Calculate the mass of 400.
mL of carbon dioxide collected over
water at 30° C and 749 mm Hg.
Solution:
PT = Pgas + Pwater= 749 mmHg
R = 0.0821 L·atm/mol·K
Pgas = 749 mmHg–31.8 mmHg
= 717 mmHg
V = 400.0 L
22.
T = 30° C + 273 = 303 K
PV = nRT
n = PV/RT
n = 717 mm x 1 atm/760 mm x 400.0 mL x
1L/10 ³mL/(0.0821 L·atm/mol·K x 303 K)
n = 0.0152 mol CO2
n = 0.0152 mol CO2 x 44.01 g CO2/1 mol
CO2
= 0.669 g CO2
23.
Exercise
1. Determine the total pressure of a
gas mixture that contains oxygen,
nitrogen, and helium if the partial
pressures of the gases are:
PO2 = 20.2 kPa
PN2 = 46.7 kPa
PHe = 26.7 kPa
24.
2. A 10 L flask at 298 K contains a
gaseous mixture of CO and CO2 at a
total pressure of 1520 mm of Hg. If
0.20 mole of CO is present, find the
partial pressure of CO and that of
CO2?
28.
Objectives
• Determine how the amount of gas in
a fixed volume at a fixed pressure
and temperature depends upon the
identity of the gas.
• To do calculations involving
Avogadro’s Law.
29.
Unlocking of Words
• Moles- another name for grams.
• Temperature- a measure of the
average kinetic energy of the
particles of a substance.
• Volume- the amount of space
occupied by something or within a
container.
30.
Lesson
• Amedeo Avogadro stated that
the volume of a gas is directly
related to its number of moles
when temperature and pressure
remain unchanged.
31.
• If the moles of a gas are doubled,
then the volume will double as long
as the pressure and temperature
remain the same.
• To illustrate these two conditions,
you may write:
V1=V2
n1 n2
32.
Activity
Problem 1: A balloon containing 2
moles of helium has a volume of
880 ml. What is the new volume
after 4 more moles of helium are
added to the balloon at the same
temperature and pressure?
33.
Solution: Step 1
Initial condition Final condition
V1= 880 ml V2=?
n1= 2 moles n2= 6 moles
Step 2
V2= 880 ml x 6 moles =2640 ml
2 moles
34.
Problem 2:
What volume of O2 measured at 1.86
x 106 Pa and 375 K, is needed to
react completely with 1.78 L of H2,
measured at the same pressure and
temperature, to give H2O?
35.
Solution:
2H₂ O₂ → 2H₂O
The volume of O₂ needed is
1.78 L H₂ (1L O₂ · 2L H₂)
= 0.890 L O₂
36.
Exercise
1. How many molecules of O2 are
present in 1.00L of O2 at STP?
2. Calculate the number of moles of
ammonia gas, NH3, in a volume of
80 L of the gas measured at STP.
40.
Objectives
• To experimentally determine the
volume of one mole of a gas at
standard temperature and pressure.
• To experimentally determine the
value of the gas constant, R.
• To calculate the standard molar
volume of a gas from accumulated
data.
41.
Unlocking of Words
• Molar mass- the mass of one mole
of an element or compound equal to
the atomic or formula weight.
• Molar volume- the volume in liters
of one mole of a gas at STP.
• STP- the standard gas conditions of 1
atm of pressure and 273 K.
42.
Lesson
• At STP conditions (1atm and 273K),
one mole of a gas occupies 22.4
liters.
• Molar volume is an extension of
Avogadro’s Law, w/c state that,”At
any given temp. and pressure equal
volume of any gases would contain
equal no. of moles.”
43.
Activity
Problem 1: What is the volume of 56 g
N₂ gas at STP?
Solution:
V= 56g N₂ x 1 mole N2 x 22.4 L N₂
28 g N₂ 1 mole N₂
=44.8 L N₂
44.
Problem 2:
How many liters of 0.250 moles of HCl
will occupy at STP?
Solution:
(x/0.250 mol)=(22.414L/1 mol)
0.250 mol x 22.414 L mol
X= 5.60 L
45.
Exercise
1. Find out the volume contained by
6.8 g of ammonia at STP?
2. A balloon contains 0.5 moles of pure
helium gas at standard temperature
and pressure. What is the volume of
the balloon?
46.
Solution:
1. Gram molecular mass of NH₃=17 g
Molar volume= 22.4 liters
17g : 22.4 L
6.8 g : x
x= (6.8 X 22.4)/17
x= 8.96 Liters
47.
2. Extract the data from the question:
n(He) = 0.5 mol
Vm = 22.71 L mol-1 (at STP 1 mole
of gas occupies 22.71 L)
V(He) = ? L
Write the equation:
V(He) = n(He) x Vm
Substitute in the values and solve:
V(He) = 0.5 x 22.71 = 11.4 L
49.
Objectives
• Demonstrate the ability to use the
ideal gas content to a basic
calculation and those that involve
density and molecular mass.
• Calculate the amount of gas at any
specified conditions of pressure,
volume and temperature.
50.
Unlocking of Words
• Ideal gas- an imaginary gas whose
behavior is described by the gas
laws.
• Ideal gas law- a law that combines
the 4 meausrable properties of a gas
in the equation
PV= nRT
51.
Lesson
• When the temperature, pressure and
volume of a gas areknown, ideal gas
equation can be use.
• The ideal gas equation, PV=nRT,
illustrates a direct relationships
between volume, temperature and
the no. of moles of a gas.
52.
• Volume and pressure are inversely
related.
P= pressure in atom
V= volume in liter
n= no. of moles of gas
T= kelvin temperature
R= 0.082 L atm/Kmol
53.
Activity
Problem 1: How many molecules are
there in 985 mL of nitrogen at 0.0° C
and 1.00 x 10-6 mmHg?
Solution:
P = 1.00 x 10-6 mmHg
T = 0.0° C + 273 = 273 K
V = 985 mL
R = 0.0821 L·atm/mol·K
54.
PV = nRT
n = PV/RT
n = 1.00 x 10-6 mm x 1 atm/760 mm x
985 mL x 1 L/103 mL/ (0.0821
L·atm/mol·K x 273 K)
= 5.78 x 10-11 moles N₂
n= 5.78 x 10-11 moles N₂ x 6.02 x
1023 N₂ molecules/1 mol N₂
= 3.48 x 1013 N₂ molecules
55.
Problem 2: Calculate the mass of
15.0 L of NH3 at 27° C and 900. mm
Hg.
Solution:
P = 900. mm Hg
T = 27° C + 273 = 300 K
V = 15.0 L
R = 0.0821 L·atm/mol·K
56.
PV = nRT
n = PV/RT
n = 900. mm x 1 atm/760 mm x
15.0 L/(0.0821 L·atm/mol·K x 300 K)
n = 0.721 moles NH3 x 17.04 g NH3/
1 mol NH3
= 12.3 g NH3
57.
Assessment
I. Choose the best answer
1. At the water’s surface, the
pressure on your body due to
the mass of air around you is
about
a. 760 KPa c. 100 mm
b. 101.3 KPa d. 760 mm
58.
2. If the volume of mole of gas
molecules remains constant,
lowering the temperature will
make the pressure
a. increase
b. increase then decrease
c. decrease
d. decrease then increase
59.
3. If the volume available to the
gas is increased, the pressure
exerted by one mole of gas
molecules will
a. increase
b. increase then decrease
c. decrease
d. decrease then increase
60.
4. How many moles of O₂ are
present in 44.8 L of O₂ at STP?
a. 1.2 moles
b. 1.4 moles
c. 2.0 moles
d. 2.8 moles
61.
5. What pressure must be applied
to 225 ml of gas at 1 atm to
reduce its volume to 100 ml?
a. 0.44 atm
b. 2.25 atm
c. 22500 atm
d. 1250 atm
63.
II. Problem solving
6. Calculate the density in g/L of
478 mL of krypton at 47° C and
671 mm Hg.
7. Calculate the mass of 400. mL
of carbon dioxide collected over
water at 30.° C and 749 mm Hg.
64.
8. Find out the volume contained by
6.8 g of ammonia at STP. (N=14,
H=1)
9. What volume of hydrogen will
react with 22.4 liters of oxygen to
form water?
10. Find the volume from the 0.250
moles gas at 200kpa and 300K
temperature.
65.
Solution
⑥
P = 671 mm Hg
T = 47° C + 273 = 320. K
V = 478 mL
R = 0.0821 L·atm/mol·K
66.
PV = nRT
n = m/MM
D = m/V = P x MM/R x T
D = 671 mm x 1 atm/760 mm x
83.80 g/mol/(0.0821 L·atm/mol·K
x 320. K)
= 2.82 g/L
67.
⑦
PT = Pgas + Pwater = 749 mm Hg
R = 0.0821 L·atm/mol·K
Pgas = 749 mm Hg – 31.8 mm Hg
= 717 mm Hg
V = 400.0 L
T = 30.° C + 273 = 303 K
68.
n = PV/RT
n = 717 mm x 1 atm/760 mm x
400.0 mL x 1 L/10³ mL/(0.0821
L·atm/mol·K x 303 K)
n = 0.0152 mol CO2
n = 0.0152 mol CO2 x 44.01 g CO2/
1 mol CO2
= 0.669 g CO2
69.
⑧
Gram molecular mass of NH3 = [N =
1 x 14)] + [H = (3 + 1)] = 14 + 3
= 17 g
Molar volume = 22.4 liters
Volume of 6.8 g of ammonia at STP
= ?
70.
The ratio between mass and volume
is as follows:
17 g : 22.4 liters
6.8 g : x
x = (6.8 x 22.4) / 17
= 8.96 Liters
71.
⑨
2H2 (g) + O2 (g) → 2H2O (l)
From the equation, 2 volumes of
hydrogen react with 1 of oxygen or
2 × 22.4 liters of hydrogen react with
22.4 liters of oxygen.
The volume of hydrogen that will
react is 44.8 liters.
72.
⑩
P = 200 kPa n = 0.250 mol
T = 300K R = 8.314 J K-1 mol-1
Volume(V) = nRT / P
= (0.250 x 8.314 x 300) / 200
= 623.55 / 200
V = 3.12 L
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