This document discusses the properties of gases and the gas laws. It explains that gases have higher energy, lower density, and flow to fill their container compared to liquids and solids. The document also describes how temperature and pressure are measured, noting that pressure is measured using a barometer that reads the height of mercury. It then explains the gas laws of Boyle's Law and Charles' Law, which describe how the volume of a gas changes with pressure and temperature respectively when other variables are held constant.

1. •Copyright Sautter 20151

2. GASES & THEIR PROPERTIES
THE GAS LAWS
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3. WHAT MAKES A GAS DIFFERENT FROM SOLIDS AND
LIQUIDS ?
• (1) ENERGY STATE - GASES HAVE A HIGHER
ENERGY CONTENT
• (2) DENSITY - GASES HAVE LOW DENSITY
• (3) GASES ARE FLUIDS - THEY FLOW AND TAKE THE
SHAPE OF THEIR CONTAINER (SO DO LIQUIDS)
• (4) THEY RESPOND NOTABLY TO CHANGES IN
TEMPERATURE AND PRESSURE
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4. HOW ARE TEMPERATURE AND PRESSURE
MEASURED ?
• TEMPERATURE IS MEASURED WITH A
THERMOMETER (OF COURSE !)
• PRESSURE IS MEASURED WITH A
BAROMETER. IT ALLOWS MERCURY TO BE
PUSHED UP A VERTICAL GLASS TUBE BY
GAS PRESSURE AND THEN THE HEIGHT OF
THE MERCURY IN THE TUBE IS READ.
PRESSURE IS THEREFORE OFTEN
MEASURED IN LENGTH UNITS SUCH AS
MILLIMETERS, CENTIMETERS OR INCHES.
• YOU HAVE CERTAINLY HEARD
TEMPERATURE AND BAROMETER
READING DURING WEATHER REPORTS ! 4

5. TORRICELLI’S BAROMETER
• Hg LEVEL
• NORMAL AIR
PRESSURE:
• 1 ATM
• 760 MM OF Hg
• 29.92 INCHES
• 14.7 PSI
• 101.3 KPa
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6. HOW DO GASES RESPOND TO
TEMPERATURE & PRESSURE ?
• AS THE TEMPERATURE OF A GAS
INCREASES, ITS VOLUME INCREASES
(DIRECT)
• AS THE PRESSURE ON A GAS INCREASES,
ITS VOLUME DECREASES (INVERSE)
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7. VARIABLES WHICH EFFECT GAS BEHAVIOR
• (1) VOLUME (LITERS)
• (2) PRESSURE (ATM OR MM OF Hg)
• (3) TEMPERATURE (DEGREES KELVIN)
• (4) QUANTITY OF GAS (MOLES)
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8. HOW DO CONFINED GASES AT A CONSTANT
TEMPERATURE RESPOND TO PRESSURE CHANGES ?
• AS PRESSURE GOES UP, VOLUME GOES DOWN
(INVERSE)
• BOYLE’S LAW SAYS:
• P1 x V1 = P2 x V2
• PRESSURE 1 AND 2 MUST BE IN THE SAME
UNITS
• VOLUME 1 AND 2 MUST BE IN THE SAME UNITS
INVERSE!!
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9. HOW DO CONFINED GASES AT A CONSTANT
TEMPERATURE RESPOND TO PRESSURE
CHANGES ? (CONT’D)
AN INVERSE RELATIONSHIP
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10. HOW DOES TEMPERATURE EFFECT THE VOLUME
OF A FIXED QUANTITY OF GAS AT A CONSTANT
PRESSURE ?
• AS TEMPERATURE GOES UP, VOLUME GOES
UP (DIRECT)
• CHARLES LAW SAYS:
• V1 / T1 = V2 / T2
• VOLUMES 1 AND 2 MUST BE THE SAME UNITS
• TEMPERATURES 1 AND 2 MUST BE IN KELVIN
KELVIN
RULES
•CHARLES
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11. Volume
T
E
M
P
E
R
A
T
U
R
E
- 273 0C
Absolute Zero
No Gas is Ideal
real gases liquefy before
absolute zero
An ideal gas would
shrink to zero volume
at absolute zero
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12. WHAT IS KELVIN TEMPERATURE ?
• KELVIN TEMPERATURE STARTS AT ABSOLUTE
ZERO (- 273 DEGREES CELSIUS)
• AT ABSOLUTE ZERO, NO HEAT IS PRESENT IN THE
SYSTEM (A CONDITION WHICH CAN NEVER BE
ACHIEVIED!)
• ALMOST ALL SCIENTIFIC CALCULATIONS
INVOLVING TEMPERATURE USE THE KELVIN
SCALE WHICH IS SOMETIMES CALLED THE
ABSOLUTE TEMPERATURE SCALE.
• KELVIN = 273 + DEGREES CELSIUS
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