1. Chapter 13 States of Matter 13.1 The Nature of Gases
13.2 The Nature of Liquids
13.3 The Nature of Solids
13.4 Changes of State
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2. Kinetic Theory and a Model for Gases
Do Now:
Which of the three states of matter has most energy? Why?
What are some properties of gases?
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3. Kinetic Theory and a Model for Gases
Kinetic Theory of Gases
SIZE:
- tiny particles (so small, considered to have no size relative to each other)
far away from each other
no attraction or repulsion
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4. Kinetic Theory and a Model for Gases
Kinetic Theory of Gases
MOTION:
Particles are in constant, rapid, and random motion.
When they collide no energy is lost (elastic collisions)
When they collide with the walls of a container, they cause pressure.
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5. Kinetic Theory and a Model for Gases
Kinetic Theory of Gases
ENERGY:
- Kinetic Energy of gases is determined by:
KE = 1/2 mv2
M= mass v= velocity
- Temperature is a measure of the average kinetic energy of the gas particles.
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6. Vacuum: empty space with no particles and no pressure.
Gas Pressure
Gas pressure results from the force exerted by a gas per unit surface area of an object.
Vacuum: empty space with no particles and no pressure.
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7. Pressure: Measured using: Barometer Gas Pressure
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8. The SI unit of pressure is the pascal (Pa).
Gas Pressure
The SI unit of pressure is the pascal (Pa).
Normal atmospheric pressure is kPa.
Two older units of pressure are commonly used.
millimeters of mercury (mm Hg)
atmospheres (atm)
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9. Gas Pressure
One standard atmosphere (atm) is the pressure to support 760 mm of mercury in a mercury barometer at 25°C.
1 atm = 760 mm Hg = kPa.
STP is 0°C and a pressure of kPa, or 1 atm.
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10. Converting Between Units of Pressure
Sample Problem 13.1
Converting Between Units of Pressure
A pressure gauge records a pressure of 600 kPa. Convert this measurement to
a. atmospheres
b. millimeters of mercury
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11. Calculate Solve for the unknowns.
Sample Problem 13.1
Calculate Solve for the unknowns. 2
Multiply the given pressure by the conversion factor.
b. 600 kPa × = 4501 mm Hg
101.3 kPa
760 mm Hg
1 atm
a. 600 kPa × = 5.9 atm
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12. Kinetic Energy and Temperature
Average Kinetic Energy
Gas particles are always moving
Their speed depends on the mass of particles
On average lighter gases move FASTER than heavier gases (have same average kinetic energy so they need higher velocity to make up for less mass)
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13. Interpret Graphs
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14. Kinetic Energy and Temperature
Average Kinetic Energy
The average kinetic energy of the particles in a substance is directly related to the substance’s temperature.
Absolute zero (0 K, or –273.15oC) is the temperature at which the motion of particles theoretically ceases.
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15. Kinetic Energy and Temperature
Average Kinetic Energy and Kelvin Temperature
The Kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles of the substance.
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16. END OF 13.1
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