Chem 115 General Chemistry

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Chem 115 General Chemistry

• Instructor Spencer Anthony-Cahill
• Office CB440
• Office hrs M 830-930am W 1-2pm Th 3-5pm
• e-mail sacahill_at_chem.wwu.edu
• http//atom.chem.wwu.edu/sacahill/115

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Chem 115 General Chemistry

• Lecture MWThF 11-1150pm in SL140.
• Russo and Silver 2nd Ed
• Get ATUS login for campus computers
• Lab Mondays 2-5pm and Tuesdays 11-2pm
• Get Lab Manual
• Get safety goggles
• First lab meeting 4/8
• Safety quiz check in density lab

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Chem 115 Exams/Grading

• 540 points possible
• Three midterms _at_ 100 pts each
• Cumulative Final exam _at_ 150 pts
• Labs 90 pts total
• Grade on a curve if necessary where median grade
  is C/C
• To pass you must complete all labs

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Chem 115 Labs

• Labs M 2-5pm or T 11am-2pm in CB 210/220. You
  will need to get a lab manual and a pair of
  safety goggles BEFORE you come to the first lab
  meeting (next Mon 4/8 or Tue 4/9).
• Safety regulations require that (1) goggles be
  worn at all times in lab, (2) shorts, short
  skirts, sandals and open-toe shoes are not
  allowed in the labs.

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Chem 115 General Chemistry

• You will need a calculator that has exponent and
  log functions. Most of the problems in the text
  and on exams require familiarity with algebra and
  exponential equations. The Tutorial Center (OM
  387) can offer assistance to those students who
  need to brush up on these skills.

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Chem 115 General Chemistry

• Schedule of lecture topics will appear on web
  site soon.
• The best preparation for exams is working
  homework problems from the text.
• If your notes are unclear, if you are struggling
  with the homework, if you feel overwhelmed
  COME TO OFFICE HRS!

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A strategy for success in Chem 115

• 1- attempt problems in text
• 2- struggle, hate life (but not too long)
• 3- obtain clarification
• 4- put new understanding into practice (solve
  more problems)
• 5- identify next conceptual hurdle
• 6- repeat steps 2-5
• ALLOW ENOUGH TIME FOR THIS CYCLE BEFORE EXAMS!!!

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Chem 115 Course Content

• This introductory course focuses on two
  fundamental chemical concepts
• - atomic and molecular structure
• (rationalize/predict chemical reactivity)
• - stoichiometry (the mole)
• (solve quantitative problems in chemistry
  understand chemical composition of matter)

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What is Chemistry?

• the torture of students with copious
  incomprehensible jargon, and impossible insoluble
  problems.
• the systematic study of the properties and
  transformation of matter
• matter anything with mass that occupies space

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What is Chemistry?

• chemistry describes the composition and
  transformation of EVERYTHING you touch, taste,
  smell, and most of what you see and hear.
• we are surrounded by chemicals, we are made up of
  thousands of chemicals!

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Dihydrogen monoxide

• 1. is a major component in acid rain
• 2. can cause severe burns in its gaseous state
• 3. accidental inhalation can kill you
• 4. contributes to erosion
• 5. decreases effectiveness of automobile brakes
• 6. is found in tumors of terminal cancer patients

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Historical Perspective

• Alchemy (largely devised by Arab scholars from
  Dark Ages to Renaissance)
• forerunner to modern chemistry
• Hg and S thought of as fundamental elements
• sought transformation of baser metals into
  gold synthesis of elixirs
• developed much lab equipment and techniques

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Historical Perspective

• Friar Roger Bacon (1200 AD)
• experimentation in science is necessary
• developed gunpowder formula
• Sir Francis Bacon (1600 AD)
• wrote Novum Organum and presented the
  scientific method.

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Historical Perspective

• Robert Boyle (1661)
• wrote Sceptical Chymist
• scientific speculation is worthless without
  experimental evidence
• Antoine Lavoisier (late 1700s)
• introduced quantitative measurement into chemical
  experimentation
• considered to be the Founder of Modern Chemistry

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The Scientific Method

• What is Science?
• explanation of the properties/behavior of systems
  (natural world) in quantitative terms
• What is an hypothesis?
• an explanation for an observation speculation
  based on an educated guess

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The Scientific Method
hypothesis (must be testable)

• observation

interpret results, modify hypothesis if
necessary design new experiments to test new
hypothesis
design and execute experiments to test hypothesis
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The Scientific Method

• natural law states a measurable relationship
  (often as an equation, i.e. Ideal Gas law or
  Coulombs law)
• theory accepted explanation for natural behavior
  (i.e. atomic theory, quantum theory)

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The Scientific Method

• natural laws are seldom disproven, however,
  limits of applicability are often determined
  experimentally.
• theories are subject to constant revision as
  experimental evidence supporting or refuting the
  theory accumulates

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The Scientific Method

• It is disconcerting to reflect on the number of
  students we have flunked in chemistry for not
  knowing what we later found to be untrue
• quoted in Robert Weber Science with a Smile (1992)

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The Scientific Method Summary

• The Scientific Method is the systematic
  investigation of nature where
• results are explained in terms of general
  scientific principles
• principles are formulated from hypotheses
• hypotheses are tested by further experimentation
• sufficient empirical support elevates hypothesis
  to theory or natural law
• you gotta earn your wings every day

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In Science is there ALWAYS a Right answer?

• most of the calculations you will encounter in
  this course (suggested problems and exams) have
  right answers
• in real life researchers investigate questions
  for which there is no known answer- they propose
  a best explanation

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In Science is there ALWAYS a Right answer?

• As a scientist, you must be able to convince
  yourself and your peers that your interpretation
  is sound given the accepted body of scientific
  knowledge

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Measurement (quantitation) is central to chemistry

• metric (noun) a standard of measurement
• -metric (suffix) of or relating to an art,
  process or science of measurement
• metric (adj) of, relating to, or using the
  metric system

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The Metric System of measurement

• DIMENSION COMMON UNIT SYMBOL
• mass gram g
• length meter m
• time second s
• temperature kelvin or K deg Celsius
  ºC
• volume liter L

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The Metric Systemmetric prefixes

• Prefix Symbol Multiple Example
• nano n 10-9 nm (molecule size)
• micro m 10-6 mm (cell size)
• milli m 10-3 mL (flu shot)
• centi c 10-2 cm (ski length)
• kilo k 103 kg (weights)
• mega M 106 MW (power)
• giga G 109 GB (memory)
• prefix base unit multiple base unit

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SPEED LIMIT

• 188,000
• (is this fast or slow?)

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SPEED LIM IT

• 188,000
• furlongs per fortnight

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How confident are we in our measurements?

• are they ACCURATE?
• conformity to standard or true value
• are they PRECISE?
• reproducible, within error tolerances
• How many of the numerals in the measurement are
  SIGNIFICANT DIGITS

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Significant Figures (or Sig Figs)

• represent the numerals that can be accurately
  measured (limited by equipment)
• there are rules for reporting Sig Figs in
  calculations (see text). In a nutshell
• a calculated value can have no more Sig Figs
  than the least number of them in the data