Matter, Energy, and Heat Basics

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Chapter 1

• Matter, Energy, and Heat Basics

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Matter

• Any substance that has weight, mass, and occupies
  space.
• Called an element when in the form of only one of
  the naturally occurring substances.
• The atom
• Smallest particle of an element
• Also considered to be matter
• Can exist in any one of three physical states
• Solid, liquid, or gas

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Solids

• A substance that has definite volume and
  sufficient mechanical strength.
• Exert all their forces in the downward direction
  toward either the surface on which they are
  resting or toward the earth.

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Solids

• A block of ice.

• A piece of wood.

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Liquids

• Liquids have definite volumes, but do not have
  definite shapes.
• The shape a liquid takes depends on the shape of
  the container that holds it.

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Gases

• Gases have neither definite volume nor definite
  shape.
• Gas molecules have little attraction for each
  other the gas will completely fill any vessel
  that contains it.
• A gas exerts pressure in all directions against
  the walls of the container that holds it.
• Gas laws determine the behavior of contained
  gases.
• Boyles Law
• Charles Law
• Daltons Law

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Gases

• Gas molecules exert pressure on the walls of a
  balloon.

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Boyles Law

• States that there is a definite relationship
  between the pressure and volume of a gas if the
  temperature is kept constant.
• States that the pressure and volume of a gas are
  inversely related
• If the volume is decreased, the pressure will
  increase
• If the volume is increased, the pressure will
  decrease

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Charles Law

• States that there is a definite relationship
  between the volume and temperature of a gas if
  the pressure is kept constant
• If the volume increases, the temperature
  increases
• If the volume decreases, the temperature
  decreases
• States that there is a definite relationship
  between the pressure and temperature of a gas if
  the volume is kept constant
• If the pressure increases, the temperature
  increases
• If the pressure decreases, the temperature
  decreases

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Daltons Law

• States that the total pressure of a confined
  mixture of different gases is equal to the sum of
  the pressures of each gas in the mixture.

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Daltons Law
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First Law of Thermodynamics

• States that energy cannot be created or
  destroyed, but can be converted from one form to
  another.
• Simply stated, when one form of energy is
  generated, it is done so at the expense of
  another energy form.

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Second Law of Thermodynamics

• States that energy tends to degrade into
  low-level heat energy.
• Heat energy is a byproduct of energy conversion
  and flows from a warmer substance to a cooler
  substance.

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Work

• Work is defined as the force exerted times the
  distance an object is moved.
• Work occurs when a force moves a mass a certain
  distance
• If no movement results, no work is being done

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Work
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Power

• Power is the rate of doing work, which is the
  amount of work per unit time.
• The term horsepower (hp) is used to measure units
  of power
• During the 18th century, it was determined that a
  horse could lift 33,000 pounds to a height of 1
  foot in one minute
• Lifting 33,000 pounds to a height of 1 foot in 30
  seconds would therefore be equal to 2 horsepower

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British Thermal Units

• Heat content is measured in British thermal units
  (Btu)
• The Btu is defined as the amount of heat required
  to raise one pound of water 1 degree Fahrenheit
• Raising the temperature of one pound of water
  from 68F to 70F would therefore require 2 Btu
  of heat energy

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British Thermal Units
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Temperature Scales

• On the Fahrenheit temperature scale, water boils
  at 212 degrees and freezes at 32 degrees.
• On the Celsius temperature scale, water boils at
  100 degrees and freezes at 0 degrees.
• Absolute zero, the temperature at which all
  molecular movement stops, is 460F or 273C
• On the Rankine and Kelvin scales, absolute zero
  is at 0 degrees (460F).

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Temperature Scales
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Conduction

• The heat transfers from one molecule to another
  within the substance.
• Metallic substances conduct heat better than
  nonmetallic substances.
• Good conductors of heat are typically good
  conductors of electricity.

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Conduction
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Convection

• Convection is the transfer of heat by a flowing
  medium.
• Heat transfer by convection takes place in
  liquids and gases, typically water and air.
• The process of convection can be sped up by using
  fans or pumps.

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Convection
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Radiation

• Heat that moves in the form of straight rays
• These rays produce heat when they come in contact
  with a surface without heating anything in their
  path

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Radiation
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Sensible Heat

• Heat transfers that can be sensed with a
  thermometer
• Changing the temperature of air from 78F to 72F
• Changing the temperature of water from 70F to
  75F
• Changing the temperature of steam from 220F to
  230F
• The state of the substance remains unchanged.

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Latent Heat

• In this process, heat is known to be added, but
  no temperature rise is measured.
• It results in a change of state with no change in
  temperature
• Changing ice at 32F to water at 32F
• Changing water at 212F to steam at 212F
• Latent heat transfers cannot be measured with a
  thermometer.

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Latent Heat
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Pressure

• The force that is exerted on the walls of a
  vessel.
• Measured in force per unit area
• Atmospheric pressure is 14.7 pounds per square
  inch
• Gauge pressure (PSIG) reads 0 psi at atmospheric
  pressure
• Absolute pressure (PSIA) reads 14.7 at
  atmospheric pressure
• Vacuum pressure is a reading below atmospheric
  pressure