ENVS 101: Introduction to Environmental Science

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What you see Pet dog going crazy scratching
himself

• a hypothesis supported by repeatable evidence,
  Scratching Dog Theory
• Dogs that scratch have fleas

How Science Works....
Test the Hypothesis Buy Pluto a flea-collar
Control Pluto without a flea
collar Treatment Pluto with a
flea collar Replication!!! 30 Plutos!

• Educated guess
• He has fleas.
• or
• He has dry skin. or

observations
theories

• But Remember.
• conclusions either reject or support hypothesis,
  never prove it!
• (have we ruled out dry skin??)

SCIENTIFIC METHOD
conclusions

• Interpret your experimental results
• No more scratching, your carpet is a flea
  graveyard!

questions
What you ask I keep a clean house, so whys he
scratching?
experimentation
hypotheses
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Experimentation...

• Allows us to study causation
• Not just correlation
• Lab studies
• Field studies
• experimental (treatment) group
• The treatment where you manipulate the variable
  of interest
• Control Group
• Do every thing you did in the experimental group
• .except, leave out the variable of interest
• Do analysis (usually use stats.)

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Scientific Measurements
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Uncertainty in Measurement

• Many properties of matter are quantitative
• Associated with a number.
• Units used in science are the metric system.
• SI Units
• Todays system developed in 1960.

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Physical Quantities

• Powers of ten are used for convenience with
  smaller or larger units in the SI system.

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Prefixes

• Need to memorize some of the above selected
  prefixes and be able to convert from one prefix
  to another.

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Temperature

• Fahrenheit Define 32oF as the freezing point of
  water and 212oF as the boiling point of water at
  sea level.
• Kelvin Define 0K as the lowest attainable
  temperature of -273.15oC (absolute zero).
• Dont use oK.

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Volume
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The Density Concept

• Each cube represents a volume of 1 cm3. As the
  mass increases, the density increases.

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We will figure out the density of zinc in lab

• Density
• Used to characterize substances.
• Defined as mass divided by volume

• Units g/cm3, g/mL, g/L.
• Density of water is 1.00 at 250C.
• Density is temperature dependent!

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Volume by Displacement

• The difference between the initial and final
  water levels is equal to the volume of the solid
  jade.

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Volume by Displacement

• The volume of water displaced is equal to the
  volume of oxygen gas produced by the sample.

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Precision and Accuracy in measuring the density
of zinc

• Precision
• How closely individual measurements agree with
  one another.
• Accuracy
• How closely individual measurements agree with
  the correct value.

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Heat and Specific Heat

• Heat measures the total energy of a system.
• Temperature measures the average energy of a
  system.
• Specific Heat Amount of heat (in calories)
  necessary to raise the temperature of 1g of any
  substance by 1oC.

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Heat and Specific Heat

• Each cube represents 1 g of substance receiving 1
  cal of heat. The temp. change varies with the
  substance.