General Chemistry the Central Science

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General Chemistrythe Central Science Brown
LeMay Chapter One Introduction, Matter
Measurement
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• Molecular Perspective
• Classifications of Matter States, Pure
  Substances, Mixtures, Elements, Compounds
• Properties of Matter
• Units of Measurement SI Units, Derived Units,
  Uncertainty, Dimensional Analysis

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• Atoms Molecules -- basic nature of
  chemistry -necessary to understand the nature of
  matter art, medicine, agriculture, environment,
  home
• Classifications of Matter -states gas,
  liquid, solid (H) -pure substance fixed
  composition/distinct properties (elements or
  compounds) -elements cannot be decomposed to
  simpler substances -compounds combination of
  two or more elements -mixture combination of
  two or more pure substances (heterogeneous
  homogeneous/solutions)

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Gas Liquid Solid
no shape, no volume
volumeno shape
volume shape
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• Elements -112 elements known -listed on
  periodic table with symbols (H) -arranged in a
  particular order such that closely related
  elements are grouped
• Compounds -two or more elements chemically
  combined -law of constant composition or
  definite proportions eg. water is always 11
  H and 89 O

while peroxide is 6 H and 94 O
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(No Transcript)
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• Mixture Physical combination of two or more
  pure substances which can be physically
  separated into the components
• Heterogeneous -composition, properties,
  appearance vary -non-uniform in appearance
• Homogeneous -uniform appearance/properties but
  may vary between different samples -a
  solution

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no
yes
yes
no
no
yes
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• Properties of Matter -Physical Properties --
  color, odor, density, b.pt. -Chemical Properties
  -- chemical changes occur -Intensive Properties
  -- do not depend upon quantity of material
  present temp, m.pt., density -Extensive
  Properties -- dependent upon the quantity of
  material present mass, volume
• Changes of Matter -Physical -- appearance
  changes but not composition -Chemical --
  transformation into chemically different
  substance

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Scientific Method
Find Patterns, Trends, Laws
Observations Experiments
Formulate Test Hypothesis
Theory
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Units of Measurement
SI Units
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Selected Prefixes
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Temperature
373K
100 C
212 F
273K
0 C
32 F
Kelvin Celsius Fahrenheit
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Derived Units -- combinations of other units

• Volume -SI unit for volume is m3 -1 L 1 dm3
  -1 mL 1cm3
• Density -amount of mass in a unit
  volume -combination of mass and volume
  units -typically g/mL for solids and liquids
  g/L for gases

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Practice Exercise 1.3 (pg. 18) 15.0 g of
ethanol needed, density 0.789 g/mL, how many mL
of ethanol needed?
need a volume unit, mL, we have a mass unit, g,
and a combination unit, g/mL
15.0 g x 1 mL 0.789 g
19.0 mL (19.0110)
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Uncertainty in Measurement

• Precision vs Accuracy -Precision -- agreement of
  measurements -Accuracy -- proximity to true value

good precision poor precision good
precisiongood accuracy poor accuracy poor
accuracy
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1
2
3
2.55
2.5
3
1
2
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Significant Figures
1. all non-zero digits are significant
1.2357 2. zeros between non-zero digits are
significant 1.20054 3. zeros to the left of
the first non-zero digit in a number are
not significant 0.0023 4. when a number ends
in zeros to the right of decimal point, the
zeros are significant 1.2300 5. when a number
ends in zeros which are to the left of the
decimal those zeros may or may not be
significant 2000 or 2000 or 2000 or 2000
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Use in Calculations

• multiplication division -result reported to no
  more total sig. digits than the piece of data
  with the least number of digits
• addition subtraction -result reported to same
  number of significant decimal places as the
  piece of data with the least number of
  significant decimal places

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Use in Calculations

• multiplication division -result reported to no
  more total sig. digits than the piece of data
  with the least number of digits (1.27)(2.3)
  2.921 2.9
• addition subtraction -result reported to same
  number of significant decimal places as the
  piece of data with the least number of
  significant decimal places 1.0 2.15 3.468
  6.618 6.6

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Dimensional Analysis

• 1 ft 12 in

• 1 ft 12 in 1 ft 1 ft

• 1 12 in or 1 1 ft
  1 ft 12 in

conversion factors
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• conversion factors convert between two
  different units

Convert 56 inches to feet.
56 in x 1 ft 12 in
4.7 ft
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Practice Excersize 1.8 pg 26 Convert 500.0 mi
to km
1. need a conversion factor
1 mi 1.6093 km
500.0 mi x 1.6093 km 1 mi
2. set up to cancel mi
3. do the math, cancel the appropriate units
500.0 mi x 1.6093 km 804.6 km 1 mi
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Convert the volume of a 10 m x 10 m x 10 m room
to liters.
1000 m3 x ?
1 dm3 1 L
1 dm 0.10 m
1000 m3 x 1 dm x 1 dm x 1 dm
1.0 x 106 dm3 0.10 m 0.10 m
0.10 m
1 dm3 0.0010 m3
1.0 x 106 dm3 x 1 L 1.0 x 106
L 1 dm3
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Problems

• If I weigh 52.3 kg, how many grams do I weigh?
• If a tennis ball is served at 140 mph, what is
  its speed in m/s?
• You have a 40 lb baggage limit, the scale reads
  17.97 kg. Are you over or under?
• Convert 2.5 L to cm3

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Problems

• Glycerol is a viscous, sweet-tasting liquid. In
  an experiment, a 25.0 mL sample was found to
  weigh 31.6 g. What is the density of
  glycerol?(2.60)
• Diethyl ether has a density of 0.713 g/mL. What
  volume of diethyl ether is needed to equal 28.0
  g?(2.64)

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Problems

• The density of the sulfuric acid solution of a
  fully charged lead storage battery is about 1.28
  g/mL. What is the mass of the solution whose
  volume is 1.50 L? (2.89)
• The density of red blood cells is about 1.093
  g/cm3, somewhat higher than that of blood plasma.
  What is the mass of cells whose volume is 5.67
  cm3?(2.88)

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Problems

• To identify a metal, an experimenter placed a
  32.6 g sample in a grad. cylinder. He then
  poured in 25.0 mL of water, covering the metal
  and bringing the liquid level in the cyliner to
  28.7 mL. What is the density of the metal?
  (2.62)
• You are buying carpet _at_ 15.00/sq. yd for a 1500
  sq. ft house. How much will it cost?

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Problems

• If liquid nitrogen has a boiling point of 77K,
  and the temperature is -300F, will it be a
  solid, liquid or gas?
• A 175 lb patient is to undergo surgery and will
  be given an anesthetic intravenously. The safe
  dosage of anesthetic is 12 mg/kg of body weight.
  Determine the maximum dose of anesthetic that
  should be used.