AssignmentAssignmentAssignmentAssignment

Complete pre-assessment test.Read Chapter 10, pp.302-325, and

define vocabulary.

Learning LogLearning LogLearning LogLearning Log

Write down at least 5 things you know

about gases.

Gases are a part of our everyday Gases are a part of our everyday lifelifeGases are a part of our everyday Gases are a part of our everyday lifelife

I. Physical Properties

(p. 303 - 312)

Ch. 10 & 11 - Ch. 10 & 11 - GasesGases

Kinetic-Molecular TheoryKinetic-Molecular TheoryKinetic-Molecular TheoryKinetic-Molecular Theory

States that the particles of matter are always in motion.

Can be used to explain the properties of solids, liquids and gases based on the energy of particles and the forces that act between them.

A. Kinetic-Molecular Theory of A. Kinetic-Molecular Theory of GasesGasesA. Kinetic-Molecular Theory of A. Kinetic-Molecular Theory of GasesGases

Ideal gas – an imaginary gas that perfectly fits all the assumptions of the kinetic-molecular theory

(5) Assumptions - Particles in an ideal gas• 1. Are very far apart - gases are

mostly empty space• 2. Have elastic collisions.

A. Kinetic-Molecular Theory of A. Kinetic-Molecular Theory of GasesGasesA. Kinetic-Molecular Theory of A. Kinetic-Molecular Theory of GasesGases

• 3. are in constant, random, straight-line motion.

• 4. don’t attract or repel each other.• 5. have an avg. KE directly related to

Kelvin temperature.KE = ½ mv2

all gases at same temp have same KE

lighter gases have higher speeds than heavier gases

B. KMT and the Nature of B. KMT and the Nature of GasesGasesB. KMT and the Nature of B. KMT and the Nature of GasesGases Expansion – gases expand to fill any

container.• random motion, no attraction

Fluidity -gases are fluids (like liquids).• no attraction

Low density - gases have very low densities. (1/1000)• lots of empty space, particles far apart

B. KMT and the Nature of B. KMT and the Nature of Gases Gases B. KMT and the Nature of B. KMT and the Nature of Gases Gases

Compressibility – gases can be compressed.• lots of empty space, particles far apart

Diffusion and effusion – gases undergo diffusion & effusion.• random motion, low mass gases faster

C. Real GasesC. Real GasesC. Real GasesC. Real Gases

Real gas – does not behave completely according to the assumptions of the kinetic-molecular theory

Particles in a REAL gas…

• have their own volume

• attract each other

C. Real GasesC. Real GasesC. Real GasesC. Real Gases

Gas behavior is most ideal…

• at low pressures

• at high temperatures

• in nonpolar atoms/molecules

D. PressureD. PressureD. PressureD. Pressure

area

forcepressure

Which shoes create the most pressure?

D. PressureD. PressureD. PressureD. Pressure

Barometer• measures atmospheric pressure

Manometer• measures contained gas pressure

D. PressureD. PressureD. PressureD. Pressure

2m

NkPa

KEY UNITS AT SEA LEVEL

101.325 kPa (kilopascal)

1 atm

760 mm Hg

760 torr

14.7 psi

E. STPE. STPE. STPE. STP

Standard Temperature & PressureStandard Temperature & Pressure

0°C 273 K

1 atm 101.325 kPa-OR-

STP

F. TemperatureF. TemperatureF. TemperatureF. Temperature

ºF

ºC

K

-459 32 212

-273 0 100

0 273 373

32FC 95 K = ºC + 273

Always use absolute temperature (Kelvin) when working with gases.

Practice Problems - Practice Problems - PressurePressurePractice Problems - Practice Problems - PressurePressure

The average atmospheric pressure in Denver, Colorado, is 0.830 atm. Express this pressure (a) in mm Hg and (b) in kPa.

(a) 0.830 atm x 760 mm Hg = 631 mm Hg 1atm(b) 0.830 atm x 101.325 kPa = 84.1 kPa 1atm

Practice Problems - Practice Problems - TemperatureTemperaturePractice Problems - Practice Problems - TemperatureTemperature

Convert -273°C to Kelvin temperature.

-273 + 273 = 0 K

Convert 20 K to Celsius temperature.

20 – 273 = -253°C

Homework AssignmentHomework AssignmentHomework AssignmentHomework Assignment

Complete #17-19 on p. 327 of the textbook.