Transcript Pre-Chem ch. 1

An introduction to how science happens and the resources
we use to analyze it
 Understand how to conduct yourself in a lab, identify lab equipment, and write a
lab report.
 Identify the main branches of science.
 Read and interpret graphs.
 Understand and implement significant figures (sig figs) in conversions.
 Understand and implement the metric system, converting various measurements.
 Beaker
 Graduated Cylinder
 Forceps (NOT tweezers!)
 Erlenmeyer flask
 Beaker tongs
 Crucible tongs
 Thermometer
 Wire gauze
 Funnel
 Ring stand
 Bunsen burner
 Watch glass
 Evaporating dish
 Stir rod
 Eye dropper
 Test tube
 Test tube holder
 Investigate
 Experiments
 Observations
 Test results
Natural Science
Biological Science
Physical Science
Zoology
Physics
Earth Science
Geology
Other Branches
Botany
Other Branches
Ecology
Chemistry
Meteorology
 Pure science
 Technology
 Microscopes
 Telescopes
 Radio telescopes
 Spectrophotometers
 Particle accelerators
 Law
 Theory
 Must explain observations imply and clearly
 Experiments that illustrate the theory must be repeatable
 Must be able to predict from the theory
 Mathematics
 Quantitative statements
 Qualitative
 Model
 CAN THEY CHANGE??
 Critical thinking
 Scientific method
 Length
 Mass
 Volume
 Weight
 Line graph
 Bar graph
 Pie chart
What is the difference in the three rulers?
Are all 3 the same?
 When making a measurement, you should write down all
of the digits you know for sure plus one estimate.
 The estimate should fall in the decimal place to the right of
the smallest increment marked on the measuring device.
If a measurement is recorded properly, you should be able to tell which digits
represent increments crossed and which represent an estimate. We count the “sig
figs” in a given measurement using the “Atlantic-Pacific Rule”. Please note that this
trick only works from the perspective of North or South America.
If the decimal point is present in a given measurement, start on the Pacific side.
Count the first non-zero digit you get to and every digit thereafter:
0.000 032 750 kg
The above measurement has 5 significant digits. The “5” is the digit representing
the last increment crossed. The final “0” is the estimated digit.
The above measurement has 5 significant digits. The “5” is the digit representing
the last increment crossed. The final “0” is the estimated digit.
If the decimal point is absent in a given measurement, start on the Atlantic side.
Count the first non-zero digit you get to and every digit thereafter:
48 200 000 m
The above measurement has 3 significant digits. The “8” is the digit representing
the last increment crossed. The “2” is the estimated digit.
 How many sig figs do each of the following have?
 3
 4.5
 0.000 45
 4.500 00
 0.360 000 000
 3,600,000
 3,600,000.
 10
 10.
 10.0
 65.40
 65.4
 3.8 x 1012
 5.663 x 102
 3.8 x 10-3
 3.00 x 10-42
 3.0 x 102
 Add and subtract as you normally would
 Your answer can only be as specific your least specific number you
added/subtracted (weakest link)
 Examples:
 0.004 dm + 0.1258 dm=
 1.2 cm + 345 cm=
 45.44- 3=
 110-21=
 35.6-3.5678=
 Answer can only have as many sig figs as your number with the LEAST amount of
sig figs
 Examples:
 340m/ 0.1257 s=
 40.1 kg x 0.2453 m2
 1.03 g- 0.0456 g=
 110 x 33
 42/4.5621
 2 doz eggs
12 eggs
1 doz eggs
1.6 kg to g
4.00 cm to mm
= 24 eggs
 2500 mg to kg
 0.45 dm to cm
 3,567.34 m to km