Bell Ringer

1
Bell Ringer

• The gas with the largest volume at STP is
• 10.0 g He
• 10.0 g Ne
• 10.0 g Ar
• 10.0 g Kr

(56.0 L He)
1 mol He
22.4 L He
He
10.0 g He
56.0 L He
x
x

4.00 g He
1 mol He
Source 2004 VA Chemistry EOC Exam
2
Bell Ringer

• The gas with the largest volume at STP is
• 10.0 g He
• 10.0 g Ne
• 10.0 g Ar
• 10.0 g Kr

(56.0 L He)
(11.1 L Ne)
1 mol Ne
22.4 L Ne
Ne
10.0 g Ne
11.1 L Ne
x
x

20.18 g Ne
1 mol Ne
Source 2004 VA Chemistry EOC Exam
3
Bell Ringer

• The gas with the largest volume at STP is
• 10.0 g He
• 10.0 g Ne
• 10.0 g Ar
• 10.0 g Kr

(56.0 L He)
(11.1 L Ne)
(5.61 L Ar)
1 mol Ar
22.4 L Ar
Ar
10.0 g Ar
5.61 L Ar
x
x

39.95 g Ar
1 mol Ar
Source 2004 VA Chemistry EOC Exam
4
Bell Ringer

• The gas with the largest volume at STP is
• 10.0 g He
• 10.0 g Ne
• 10.0 g Ar
• 10.0 g Kr

(56.0 L He)
(11.1 L Ne)
(5.61 L Ar)
(2.67 L Kr)
1 mol Kr
22.4 L Kr
Kr
10.0 g Kr
2.67 L Kr
x
x

83.80 g Kr
1 mol Kr
Source 2004 VA Chemistry EOC Exam
5
GAS LAWS

• Ms. Besal
• 3/10/2006

6
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
  Boyles Law.
• Explain how temperature, pressure, and volume of
  gases are all related according to the combined
  gas law.
• Solve mathematic problems about Charles Law,
  Boyles Law, and the combined gas law.

7
What are Characteristics of a GAS?
E X P A N D A B L E
Diffusible...
Fluid
Compressible
Low Density
8
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)

• 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)

Assumptions
Image Source mtv.com
9
SO FAR
S T P
Standard Temperature Pressure
273 K
1 atmosphere (atm)
10
What does PRESSURE mean?

• In Life
• Pressure a chemistry quiz every day

• In Science
• Pressure force per unit area

PSI Pounds per Square Inch
11
How else can we measure Pressure?
760 mm Hg
1 atmosphere

760 torr
101.3 kilopascals
These numbers reflect STANDARD PRESSURE
12
SO FAR
S T P
Standard Temperature Pressure
273 K
1 atmosphere (atm)
13
How can we change Gases?
Action
Variable
Heat it up/Cool it down
Temperature
Change container size
Volume
Compress or Decompress
Pressure
14
How are Temperature and Volume Related?
Initial
Final
T1
T2
Temperature
V1
V2
Volume
15
How are Temperature and Volume Related?
x
x
x
x
x
x
x
Volume
x
x
x
x
x
x
Temperature
At constant pressure temperature and volume are
directly proportional
16
Charles Law
At constant pressure temperature and volume are
directly proportional.
Temperature is always measured in Kelvin!
0ºC 273 K
17
How can we change Gases?
Action
Variable
Heat it up/Cool it down
Temperature
Change container size
Volume
Compress or Decompress
Pressure
18
How are Volume and Pressure Related?
Initial
Final
V1
V2
Volume
P1
P2
Pressure
19
How are Volume and Pressure Related?
x
x
x
x
x
x
x
Volume
x
x
x
x
x
x
Pressure
At constant temperature volume and pressure are
inversely proportional
20
Boyles Law
At constant temperature volume and pressure are
inversely proportional.
21
To Recap

• Charles Law
• Relates Temperature and Volume.

• Boyles Law
• Relates Pressure and Volume

22
THEREFORE

• Temperature, Volume, and Pressure are all related!

Combined Gas Law
23
Practice
100.0 cm3 oxygen at 10.50 kPa changes to 9.91
kPa. What is the new volume of the gas?
1.


Boyles Law!
(100.0 cm3 O2)
x
(10.50 kPa)

(9.91 kPa)
(V2)
x
V2

(100.0 cm3 O2)
x
(10.50 kPa)

106 cm3 O2
(9.91 kPa)
24
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?

798 mmHg
25
Practice
75.0 cm3 of hydrogen at 27.0ºC changed to
10.0ºC. What is the new volume of the gas?
3.


Charles Law!
Kelvin!
75.0 cm3 H2
V2

300 K
263 K
V2

(263 K)
x
(75.0 cm3 H2)

65.8 cm3 H2
(300 K)
26
Practice
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?
4.


393 K
27
Practice
140. L chlorine at 15.0ºC and 110.0 kPa changed
to 40.0ºC and 123.5 L. What is the new pressure?
5.

(140 L Cl2)
(123.5 L Cl2)
(110.0 kPa)
(P2)

288 K
313 K
P2

(140. L Cl2)
(110.0 kPa)
(313 K)
136 kPa

(288 K)
(123.5 L Cl2)
28
Practice
500.0 mL of hydrogen at 20.0ºC and 121 kPa
changed to STP. What is the new volume of the
gas?
6.


556 mL H2

29
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

30
What Should I Study?

• how pressure, temperature, and volume relate to
  each other in Boyles, 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.

31
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
  Boyles Law.
• Explain how temperature, pressure, and volume of
  gases are all related according to the combined
  gas law.
• Solve mathematic problems about Charles Law,
  Boyles Law, and the combined gas law.