Bell Ringer
The gas with the largest volume at STP is:
A. 10.0 g He
(56.0 L He)
B. 10.0 g Ne
C. 10.0 g Ar
D. 10.0 g Kr
He:
10.0 g He x
1 mol He
4.00 g He
x
22.4 L He
= 56.0 L He
1 mol He
Source: 2004 VA Chemistry EOC Exam
Bell Ringer
The gas with the largest volume at STP is:
A. 10.0 g He
(56.0 L He)
B. 10.0 g Ne
(11.1 L Ne)
C. 10.0 g Ar
D. 10.0 g Kr
Ne:
10.0 g Ne x
1 mol Ne
20.18 g Ne
x
22.4 L Ne
= 11.1 L Ne
1 mol Ne
Source: 2004 VA Chemistry EOC Exam
Bell Ringer
The gas with the largest volume at STP is:
A. 10.0 g He
(56.0 L He)
B. 10.0 g Ne
(11.1 L Ne)
C. 10.0 g Ar
(5.61 L Ar)
D. 10.0 g Kr
Ar:
10.0 g Ar x
1 mol Ar
39.95 g Ar
x
22.4 L Ar
= 5.61 L Ar
1 mol Ar
Source: 2004 VA Chemistry EOC Exam
Bell Ringer
The gas with the largest volume at STP is:
A. 10.0 g He
(56.0 L He)
B. 10.0 g Ne
(11.1 L Ne)
C. 10.0 g Ar
(5.61 L Ar)
D. 10.0 g Kr
(2.67 L Kr)
Kr:
10.0 g Kr x
1 mol Kr
83.80 g Kr
x
22.4 L Kr
= 2.67 L Kr
1 mol Kr
Source: 2004 VA Chemistry EOC Exam
GAS LAWS
Ms. Besal
3/10/2006
Lesson Objectives
•
•
•
•
•
•
•
•
You will be able to:
Name and describe 5 characteristics of gases
Identify three differences between ideal gases and real
gases.
Define the term “STP”
List 4 units for pressure measurement
Explain and describe the relationship between
temperature and pressure of gases, according to
Charles’ Law.
Explain and describe the relationship between volume
and pressure of gases, according to Boyle’s Law.
Explain how temperature, pressure, and volume of gases
are all related according to the combined gas law.
Solve mathematic problems about Charles’ Law, Boyle’s
Law, and the combined gas law.
What are Characteristics of a GAS?
: Gas Laws
In the REAL WORLD:
• Gases are fat.
(they have mass)
• Gases hog the sofa.
(they have volume)
• Gases are pushy and
have an attitude
toward other gases.
(they exert forces on
each other)
Image Source: mtv.com
In an IDEAL WORLD:
• Gases are skinny.
(they have no mass)
• Gases make
themselves invisible.
(they have no volume)
• Gases are not
confrontational.
(they do not interact…
elastic collisions)
SO FAR…
Standard Temperature & Pressure
1 atmosphere
273 K
(atm)
What does PRESSURE mean?
• In Life:
Pressure = a chemistry quiz every day
• In Science:
Pressure = force per unit area
P= F
A
How else can we measure Pressure?
SO FAR…
Standard Temperature & Pressure
1 atmosphere
273 K
(atm)
How can we change Gases?
Action
Heat it up/Cool it down
Variable
Temperature
Change container size
Volume
Compress or Decompress
Pressure
How are Temperature and
Volume Related?
Temperature
Volume
Initial
Final
T1
T2
V1
V2
How are Temperature and
Volume Related?
x
x
Volume
x
x
x
x
x
x
x
x
x
xx
Temperature
“At constant pressure… temperature and
volume are directly proportional”
Charles’ Law
“At constant pressure… temperature and
volume are directly proportional.”
V1
T1
=
V2
T2
Temperature is always
measured in Kelvin!
0ºC = 273 K
How can we change Gases?
Action
Heat it up/Cool it down
Variable
Temperature
Change container size
Volume
Compress or Decompress
Pressure
How are Volume and Pressure
Related?
Initial
Final
Volume
V1
V2
Pressure
P1
P2
How are Volume and Pressure
Related?
x
Volume
x
x
x
x x
x x
x
x x
x x
Pressure
“At constant temperature… volume and
pressure are inversely proportional”
Boyle’s Law
“At constant temperature… volume and
pressure are inversely proportional.”
P1
x
V1
=
P2
x
V2
To Recap…
• Charles’ Law:
Relates Temperature and Volume.
V1
T1
=
V2
T2
• Boyle’s Law:
Relates Pressure and Volume
P1
x
V1
=
P2
x
V2
…THEREFORE:
• Temperature, Volume, and Pressure are all
related!
P1 V1
T1
=
P2 V2
T2
Practice
1. 100.0 cm3 oxygen at 10.50 kPa changes to 9.91
kPa. What is the new volume of the gas?
P1 V1
T1
P1 V1
=
=
P2 V2
T2
P2 V2
Boyle’s Law!
(10.50 kPa) x (100.0 cm3 O2) = (9.91 kPa) x (V2)
V2 = (10.50 kPa) x (100.0 cm3 O2)
(9.91 kPa)
= 106 cm3 O2
Practice
2. 150.0 mL sulfur dioxide at 748 mmHg changes to
a new volume of 140.6 mL. What is the new
pressure of the gas?
P1 V1
P2 V2
=
T1
T2
P1 V1
=
P2 V2
(748 mmHg) x (150.0 mL SO2) = (P2) x (140.6 mL SO2)
P2 = (748 mmHg) (150.0 mL SO2)
(140.6 mL SO2)
= 798 mmHg
Practice
3. 75.0 cm3 of hydrogen at 27.0ºC changed to
–10.0ºC. What is the new volume of the gas?
P1 V1
=
T1
V1
Kelvin!
T2
V2
=
T1
75.0 cm3 H2
300 K
P2 V2
T2
=
V2
263 K
V2 = (75.0 cm3 H2) x (263 K)
(300 K)
Charles’ Law!
= 65.8 cm3 H2
Practice
4. A gas occupies a volume of 0.560 L. The
original temperature was cooled to 7.71 ºC and
the resulting volume was 0.400 L. What was
the original temperature of the gas?
P1 V1
T1
0.560 L
T1
T1 =
P2 V2
=
T2
=
0.400L
280.71 K
(0.560 L) x (280.71 K) = 393 K 120.ºC
(0.400 L)
Practice
5. 140. L chlorine at 15.0ºC and 110.0 kPa
changed to 40.0ºC and 123.5 L. What is the
new pressure?
P1 V1
P2 V2
=
T1
(110.0 kPa) (140 L Cl2)
288 K
T2
=
(P2) (123.5 L Cl2)
313 K
P2 = (110.0 kPa) (140. L Cl2) (313 K)
(288 K) (123.5 L Cl2)
= 136 kPa
Practice
6. 500.0 mL of hydrogen at 20.0ºC and 121 kPa
changed to STP. What is the new volume of the
gas?
P1 V1
P2 V2
=
T1
T2
(120 kPa) (500.0 mL H2)
293 K
=
(101.3 kPa) (V2)
273 K
V2 = (121 kPa) (500.0 mL H2) (273 K)
(293 K)
(101.3 kPa)
= 556 mL H2
For Next Class:
Homework:
Last page of Gas Laws Packet:
Problems 1-10, 11-25 ODD
QUIZ on Charles, Boyle, and Combined Gas Laws
24 points.
3 short answer/FITB problems (2 points each)
3 math problems (6 points each)
• 2 points for correct equation
• 2 points for correct math
• 2 points for correct labels
What Should I Study?
• how pressure, temperature, and volume relate to
each other in Boyle’s, Charles’, and Combined Gas
Laws.
• how to determine changing conditions using
math (practice problems & homework).
• standard conditions of temperature and pressure;
how to convert from Celsius to Kelvin, from kPa to
atm to mm Hg.
• how real gases and ideal gases differ.
Lesson Objectives
•
•
•
•
•
•
•
•
You should be able to:
Name and describe 5 characteristics of gases
Identify three differences between ideal gases and real
gases.
Define the term “STP”
List 4 units for pressure measurement
Explain and describe the relationship between
temperature and pressure of gases, according to
Charles’ Law.
Explain and describe the relationship between volume
and pressure of gases, according to Boyle’s Law.
Explain how temperature, pressure, and volume of gases
are all related according to the combined gas law.
Solve mathematic problems about Charles’ Law, Boyle’s
Law, and the combined gas law.