Chapter One

1
Chemistry 107L General Chemistry Professor
Bailey Stratton 219 x3286
Professor Jasper Freley Wells College Chemistry
Class Top Floor of Morgan Hall 1882 or 1883
2
Chemistry

• interested in the composition, structure,
  physical properties, and transformation of
  matter.

3
Goals of Chemistry

• recognize patterns in the behaviors of different
  substances
• develop models that explain these observations
• use models to predict behavior of other
  substances (whenever possible, models should be
  quantitative)
• test predictions experimentally

4
The Kinetic-Molecular Theory

• All matter consists of extremely tiny particles
  (atoms, molecules, or ions), which are in
  constant random motion.

5
Thinking About Chemistry
6

• Chemical Properties
• observed when substance undergoes a chemical
  change.

7

• Physical Properties
• measured without changing the chemical identity
  of a substance.

8

• Classifications of Properties
• Intensive Properties
• do not depend on quantity of substance
• can be measured at any point in the system
• Extensive Properties
• depend on amounts of substance
• value for entire system equals the sum of the
  individual parts of the system

melting point boiling point density
length mass volume
9
Scientific Notation

• shorthand method for working with very large and
  very small numbers.
• describe numbers as some power of ten.
• very small numbers move decimal place to right
  and count until it is to the right of the first
  non-zero digit.
• e.g. 0.0000000000001
• 1 x 10-13
• very large numbers move decimal to left and
  count until it is to the right of the first
  non-zero digit.
• e.g. 10,000,000
• 1 x 107
• conventions only 1 digit to left of decimal if
  exponent is lt3, dont use exponents

negative power of ten denotes small number
positive power of ten denotes large number
10
Metric System Measurements

• Based on powers of 10 of some basic unit

11
Dimensional Analysis

• need to convert from one type of unit to another
• e.g. 17.4 oz is how many grams?
• 17.4 oz x ? / ? g
• 16.0 oz 453.6 g (from book)

16.0 oz 453.6 g
453.6 g 16.0 oz
1 or
1
453.6 g 16.0 oz
so, 17.4 oz x
493 g
conversion factor
(in effect multiplying by one)

• note that oz cancel out leaving the desired units
  (dimensions) Dimensional Analysis.
• MAY use multiple conversion factors.

12
Dimensional Analysis
The density of mercury (Hg) is 13.6 g/cm3, and
its heat capacity is 0.140 J/g.K. What amount of
heat (in J) is required to raise the temperature
of a 5.0mL sample of Hg by 2.0K?
13
Quantitative Analytical Glassware
All quantitative measurements contain some error.
The precision of each measurement is only as
good as the measuring device.
50mL Buret (? 0.05mL)
100mL Graduated Cylinder (? 1mL)
150mL Beaker (? 10mL)
14
Significant Figures (Sig Figs)

• all experimental data has some uncertainty.
• expressed in last digit.
• all digits known with certainty plus one
  additional digit are called significant.

Length of object (cm)



22.2 cm
21
22

23
known with certainty
interpolated
Object
15
Significant Figures (Sig Figs)

• all experimental data has some uncertainty.
• expressed in last digit.
• all digits known with certainty plus one
  additional digit are called significant.

Length of object (cm)



22.2 cm
21
22

23
known with certainty
interpolated
Object



22.18 cm
21.0 21.5
22.0
22.5 23.0
16
Significant Figures (Sig Figs)

• determining number of SigFigs in a number
• . all non-zero digits are significant.
• . all zeros are significant except if they only
  locate a decimal.

• . zeros to the left of the last non-zero digit
  are not significant
• . zeros to the right of the last non-zero
  digit are only significant in numbers with a
  decimal point.

0.000123 3 SigFigs 1.23 x 10-4
123000 3 SigFigs 1.23 x 105 123000.
6 SigFigs 1.23000 x 105 0.0012300
5 SigFigs 1.2300 x 10-3
17
Mathematics with SigFigs

• Multiplication and Division
• SigFigs in answer SigFigs in quantity with
  fewest SigFigs.

2.031 x 14.2 28.840
4 SigFigs 3 SigFigs answer should be reported
with 3 SigFigs
Answer 28.8

• Addition and Subtraction
• the number of decimal places in the answer is the
  same as the number of decimal places in the
  number with the fewest places.

102.031 14.2 116.231
3 decimal places 1 decimal place answer should be
reported to 1 decimal place
Answer 116.2
(note answer has 4 SigFigs)

• DO NOT ROUND UNTIL AFTER ALL CALCULATIONS!