Mathematical Foundations in Chemistry

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Mathematical Foundations in Chemistry
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Measurement

• A chemist must know how to properly use all
  measuring devices.
• Must know how to determine the most precise
  measurement the instrument will allow.

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Measuring InstrumentsThe Ruler

• In science is the American or metric system used?
• Metric

ALWAYS
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Measuring InstrumentsGraduated Cylinders -
Liquids

• A graduated cylinder is used to measure the
  volume of a liquid.
• This is a 100 milliliter graduated cylinder (GC)
• How would you read the volume of this liquid?

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Properly Measuring a Liquid

• Because of a liquids adhesive property, a lens
  shaped meniscus forms at the surface of the
  liquid.
• When measuring liquids, measure from the
  bottom of the meniscus.

Meniscus
ALWAYS
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Proper Measurement
Inaccurate measurement when looking from top.
Proper measurement when measuring at eye level
with meniscus.
Inaccurate measurement when looking from bottom.
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Measuring InstrumentsThe Thermometer

• A THERMOMETER is used to measure the TEMPERATURE
  of a substance
• Temperature is a measure of how much KINETIC
  ENERGY the molecule of a substance have.
• KINETIC ENERGY is the energy of MOTION

Therefore THERMOMETERS measure how much ENERGY
is being given off due the MOVEMENT of molecules
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Using a Thermometer

• When you look at a regular outside bulb
  thermometer, you'll see a thin red or silver line
  that grows longer when it is hotter. The line
  goes down when colder.

Molecules Moving Faster
Increasing Temperature

• This liquid is sometimes colored alcohol but can
  also be a metallic liquid called mercury. Both
  mercury and alcohol grow bigger when heated and
  smaller when cooled.

Decreasing Temperature
Molecules Moving Slower
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How to Measure

• When measuring we always record the actual values
  that we see.
• 29 Degrees
• We ESTIMATE the next place value.
• I would estimate that the red line is 0.1 degree
  above 29 degrees.

Therefore this Thermometer reads 29.1 degrees