Chapter 1 Matter and Measurement

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Chapter 1Matter and Measurement
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What is Chemistry?

• The study of all substances and the changes that
  they can undergo
• The CENTRAL SCIENCE

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Why Study Chemistry?

• Useful for other sciences
• Required course ?
• Fun and Challenging
• Remember
• Process of Discovery
• Understand Concepts, NOT Single Facts

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Scientific Method
Observation
Question
Hypothesis
Experiment
Conclusion
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Scientific Method
Conclusion

• Natural Law
• Explains how nature behaves

• Theory
• Explains why nature behaves in a certain way

Prediction
Experiment
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Liquids
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Liquids

• Definite
• Molecules
• Not affected by

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Solids
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Solids

• Dont
• Definite
• Molecules
• Not affected by

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Gases

• Low
• Density
• Expands to
• Indefinite
• Molecules move

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The Metric SystemThe International System of
Units

• Standards of measurement
• Base units (7) Fig 1-14 p. 18
• MASS
• LENGTH
• TIME
• COUNT, QUANTITY
• TEMPERATURE
• ELECTRIC CURRENT
• LUMINOUS INTENSITY

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The Metric System

• Derived Units
• AREA
• VOLUME
• ENERGY
• FORCE
• PRESSURE
• POWER
• VOLTAGE
• FREQUENCY
• ELECTRIC CHARGE

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The Metric System

• Metric Prefixes make base unit larger or
  smaller
• Based on 10
• Math method vs. Stairs

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Conversion Practice

• Convert a volume of 12 microliters into
  centiliters
• Express a distance of 15 meters in kilometers
• Convert 83 cm into meters
• Which is the longer amount of time, 1351 ps or
  1.2 ns?
• Convert 16 dL into L

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Types of Measurements

• Mass amount of
• Expressed in
• Does not
• Weight
• Expressed in
• Changes with

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Types of Measurements

• Volume the amount of
• Many instruments to measure
• Temperature
• Degrees
• Degress

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Density

• Common ratio used in chemistry
• Physical property of a substance
• SI units

• Solid
• Liquid
• Gas

Can change due to temperature and/or pressure
changes
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Density

• Find the density of a piece of metal with a
  volume of 2.7 cm3 and a mass of 10.8 g.

2. Determine the mass of an object with a density
of 0.24 g/cm3 and a volume of 2 cm3.
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Uncertainty in Measurement

• Why are digits in measurements uncertain?
• Instruments never completely free of flaws
• Always involves estimation
• Choose the right instrument for the job
• May be estimated for you (electronic scales)
• Scale is marked but you estimate the in-between

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Uncertainty in Measurement

• Precision
• Accuracy

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Significant Digits

• All digits known with certainty plus one final
  digit which is uncertain (or estimated)
• All non-zeros are
• A zero is significant when
• It is
• It is
• A zero is not significant when
• It is
• It is

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Significant Digits - PRACTICE

• How many significant digits?
• 54.23
• 23.00005
• 0.0004
• 35000
• 0.000504
• 45.623200
• 5,000,000
• 4,000,000.1

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Significant Digits - Calculations

• Addition and Subtraction
• 1.21 5.002 10. 16.212 becomes 16
• 34.5 12.45 23.0505
• 186.31 11.1
• 12.0231 3.86
• 0.100012 120.
• 1200 12 15 0.5

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Significant Digits - Calculations

• Multiplication and Division
• The answer has as many sig figs as the number
  with the fewest sig figs
• 14.8 x 3.1 45.88 becomes 46
• 18.2 x 3.0
• 52/1.5
• 321.868783 x 1
• 2400 x 2.123
• 15000/12.354

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Scientific Notation

• Convenient way of writing very large or very
  small numbers and showing only significant
  figures
• Number between 1 10 with a power of ten
• 5120 becomes 5.12 x 103
• Move decimal point in original number to make
  number 1-10
• Move left move right -

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Scientific Notation Practice

• 123,000
• 0.000045
• 23.45
• 0.0000000003
• 1,000,000

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Scientific Notation

• Adding and subtracting
• Multiply and divide

3.38 x 103
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Conversion Factors

• Enable movement between metric system and
  English system
• See back cover of book and Appendix III
• Common conversions you should memorize
• 1 inch 2.54 cm
• 1 mile 1.609 km
• 1 kg 2.20 pounds
• 1 mL 1 cm3
• 0 K -273.15 0C
• 0F 1.8(0C) 32

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Dimensional Analysis(Problem Solving)

• Remember ALWAYS use UNITS OF MEASUREMENT in
  your work!!!
• A technique of converting between units
• Same system (metrics)
• Different systems (inches to meters)
• Chemical equations.later chapters

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Dimensional Analysis(Problem Solving)

• Conversion Factors ratio derived from the
  equality between 2 different units
• CF can be written either way

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Dimensional Analysis(Problem Solving)

• The t method

Conversion Factor
Example How many liters are in 125.6 gallons?
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Dimensional Analysis(Problem Solving)
Dimensional Analysis(Problem Solving)
How many seconds are in 4.15 hours?
If a student needs 1.5 mL of water, how many cups
does he need?