Chem 1061 Principles of Chemistry I

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Chem 1061Principles of Chemistry I
Andy Aspaas, Instructor
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About this class

• Prereq. to CHEM 1062
• More detail in underlying concepts than 1020
• Expected that you already have basic familiarity
  with chemistry concepts
• Syllabus

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Chapter 1

• Should be review, but still read carefully
• Why study chemistry?
• Practical applications
• Intellectual development
• Crossover to other fields

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The scientific method

• Problem or question what does the scientist wish
  to accomplish in research?
• Law a fundamental consistent observation
• Experimentation controlled observations, aim is
  to get consistent results that can be replicated
  and explained
• Hypothesis a tentative explanation
• Theory a tested explanation

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Matter and mass

• Matter is anything that occupies space
• Mass a measure of the amount of matter in a
  sample
• Only measured with a balance
• Weight the gravitational force a sample exerts
• Measured with a scale
• Mass is always conserved in a chemical
  transformation (reaction)

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Physical states of matter

• Solid rigid material made of closely packed,
  relatively motionless particles
• Liquid mostly incompressible fluid particles
  are in close proximity but move freely
• (fluids flow easily and change shape to occupy
  the space of their vessel)
• Gas compressible fluid particles are distant
  and fast-moving

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Changes

• Physical change form of the matter is changed,
  but not its chemical identity
• Phase changes melting, freezing, boiling,
  evaporation, condensation, sublimation
• Dissolving, like Kool-Aid into water
• Chemical change matter is changed into a
  different kind of matter

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Types of matter

• Substances cannot be separated into other types
  of matter by physical processes
• Elements cannot be decomposed into simpler
  substances by chemical changes
• Compounds composed of 2 or more chemically
  combined elements

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Types of matter

• Mixtures can be separated by physical means into
  other substances
• Heterogeneous has parts with different
  observable physical distinctions
• Homogeneous uniform in properties throughout,
  a.k.a. solutions

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Physical measurements

• Measurement comparison of physical quantity with
  a fixed standard (a unit of measurement)
• Precision how similar a number of measurements
  are
• Accuracy how close a single measurement is to
  its true value

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Significant figures

• The number of meaningful digits in a measurement,
  indicating precision of measurement
• All nonzero digits are significant
• Zeroes at the beginning of a number are not
• Terminal zeroes are if theres a decimal point
• Terminal zeroes with no decimal point usually are
  not
• Exact quantities have an infinite number of sig
  figs

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Using sig figs

• x or answer has same number of sig figs as
  measurement with least number of sig figs
• or - answer has same number of decimal places
  as measurement with least number of decimal
  places
• Exact numbers do not change number of sig figs or
  decimal places in answer
• Round answer to give correct sig figs or decimal
  places, do not round intermediate calcs

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SI units

• Metric system uses SI units of measurement
• Easy conversions between units
• All decimal based
• Power of 10 prefix

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SI base units

• Units from which all other SI units can be
  derived
• Measurement Unit Symbol
• Length meter m
• Mass kilogram kg
• Time second s
• Temperature kelvin K
• Quantity mole mol
• Electrical current ampere A
• Luminosity candela cd

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SI prefixes

• Multiple Prefix Symbol
• 106 mega M
• 103 kilo k
• 10-1 deci d
• 10-2 centi c
• 10-3 milli m
• 10-6 micro µ
• 10-9 nano n
• 10-12 pico p

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Length, mass, and time

• Meter (m) is SI base unit of length
• Nanometer (nm, 10-9 m) and Å (angstrom, 10-10 m)
  commonly used by chemists
• Kilogram (kg) mass, about 2.2 pounds
• Second (s) time - many of the fastest chemical
  reactions are finished in picoseconds (10-12 s)

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Temperature

• A measurement of the consequences of heat energy
  on a substance
• Not a measurement of heat itself
• Celsius scale most common scientific use
• Kelvin (K) SI base unit, lowest theoretical
  possible temperature is zero (absolute zero)
• Fahrenheit scale used in US
• Conversions

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Derived units

• Obtained by mathematically combining 2 or more
  other SI units
• Volume length cubed. SI unit is m3
• Traditional unit is liter (L), equal to 1 dm3
• 1 milliliter (mL) 1 cm3
• Density mass per unit volume.
• Common unit is g/cm3
• Important characteristic of a substance

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Dimensional analysis

• Systematic method of unit conversion
• Start with a single known quantity
• Multiply by conversion factors
• An equality written as a division of two units
• Arrange conversion factors so units cancel
• Unit of answer is apparent through calculation
• Estimate to make sure answer is reasonable