Matter and Energy

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Chapter 3

• Matter and Energy

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Matter

• Matter has three states
• Solid
• Fixed shape and volume
• Liquid
• Fixed volume assumes shape of container
• Gas
• No fixed shape or volume

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Physical and Chemical Properties

• Physical property is a property that can be
  measured or observed without changing the
  substance
• Chemical property is one that becomes apparent
  during a chemical reaction

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Question?

• Characterize the following as chemical or
  physical properties
• Boiling point of alcohol is 78 C
• Diamond is very hard
• Sugar ferments to form alcohol
• A copper wire conducts an electrical current

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Physical and Chemical Changes

• A Physical change involves a change in one or
  more physical properties, but no change in the
  fundamental components that make up the substance
• Gas to liquid, liquid to a solid
• A chemical change involves a change in the
  fundamental components of the substance
• Iron rusts, silver tarnishes

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Question

• Classify each as a chemical or physical change
• Iron melts
• Wood burns in are
• A rock is broken into small pieces
• Fry and egg

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Elements and Compounds

• Atom
• Smallest particle that can make up any substance
• Elements
• A pure substance composed of only one type of
  atom
• Compounds
• Two or more elements combined to make a new
  substance

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Mixtures and Pure Substances

• Mixture contains two or more substances
• Pure substance has only one element or compound
  present

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Examples

• Sand
• Tap water
• River water
• Distilled water
• Air
• Gasoline
• Copper

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Separation of Mixtures

• Two methods
• Distillation
• Filtration

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Energy and Energy Changes

• Energy is the capacity to do work
• Measured in calories (metric system) or joules
  (SI system)

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Sample Problem

• Convert 60.1 cal to joules
• 1 cal 4.184 J

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Sample problem 2

• Determine the amount of energy in joules required
  to raise the temperature of 7.40 g water from
  29.0 C to 46.0 C.
• Equation (p 75)
• Q s x m x DT
• Q is energy or heat required
• s is specific heat
• DT is change in temp in degrees C
• Tf-Ti DT

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Sample Problem 3

• A 16.0 g sample of a metal that appears to be
  gold requires 5.8 J of energy to change the
  temperature from 23 C to 41 C. Is the metal
  gold?
• Specific heat capacity for some compounds and
  elements are located in table 3.2 p 73