Welcome to the World of Chemistry

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Welcome to the World of Chemistry
Yale University Chemistry 113
Lectures Prof. Victor S. BatistaDiscussions
Dr. Iona Black Ms. Brooke
Rosenzweig Mr. Robert Snoeberger
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REGISTRATION Chem 113 students have to register
their preferences for a discussion section online
as well as in the hard copy card distributed
during the first lecture. Students will be able
to register their section or lab preference (1,
2, 3) online by following instructions at the
Online Course Information (OCI) website.
Preference selection has opened and will
close on Friday, Sept. 7 at 1230 PM. At that
time each instructor will be able to assign
students according to their preferences for
sections. The office staff will upload the
section assignments to the Online Course System
(OCS) and students will be able to see their
section on their course registration sheet.
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Wheres the Syllabus ?
https//classesv2.yale.edu/portal/
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What does Chemistry concern with ?

• Chemistry is the foundation of all molecular
  sciences
• Chemistry provides understanding, prediction and
  control of the nature and behavior of matter
• Chemistry is practical and profoundly
  philosophical
• HOW CAN SUBSTANCES BE MADE ?
• HOW DOES MATTER REACT ?!
• WHAT MATTER IS ?!!

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Chemistry Matter

• Chemistry explores the MACROSCOPIC world what
  we can see
• to understand the PARTICULATE world we cannot
  see.
• EXPERIMENTS provide insights into these worlds
  beyond what our eyes can actually see!!
• Chem 113 students are strongly encourage to take
  the lab Chem 116L

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Chemistry 116L Fall 2007   Register in Chem 116L
online through the OCS   Placement list will be
available online on September 7.   Purchase a
copy of the lab manual from TYCO (corner of Elm
Broadway), and study the first ten pages.   Next
week we have orientation and Ex. 1. at 1 pm (for
both the 12 noon and 1 pm sections). Everyone
should try to attend the orientation on the day
they are placed in Chemistry 116L. Wear shoes
!   Any questions? Need additional info? Email
Dr. G narasimhan.ganapathi_at_yale.edu
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A Chemists View Exp. I
Macroscopic
Symbolic
Particulate
2 H2(g) O2 (g) --gt 2 H2O(g)
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Chemical Properties and Chemical Change

• Burning hydrogen (H2) in oxygen (O2) gives H2O.

• Chemical change or chemical reaction
  transformation of one or more atoms or molecules
  into one or more different molecules.

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Scientific Method

• (1) OBSERVE AND QUESTION about some aspect of the
  world.
• (2) POSTULATE a tentative explanation
  (HYPOTHESIS) and
• make predictions.
• (3) TEST those predictions against
• observations of reproducible events.
• (4) REPEAT steps 2 and 3 until there are no more
  discrepancies between predictions and
  observations.
• When consistency is obtained, hypotheses become
  a theory (i.e., a coherent set of propositions
  that explain a wide class of phenomena.

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Types of Observations and Measurements

• We make QUALITATIVE observations of reactions
  changes in color and physical state.
• We also make QUANTITATIVE MEASUREMENTS, which
  involve numbers.
• Use SI units based on the metric system

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UNITS OF MEASUREMENT

• Use SI units based on the metric system
• Length
• Mass
• Time
• Temperature

Meter, m
Kilogram, kg
Seconds, s
Celsius degrees, C kelvins, K
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Units of Length

• 1 kilometer (km) ? meters (m)
• 1 meter (m) ? centimeters (cm)
• 1 centimeter (cm) ? millimeter (mm)
• 1 nanometer (nm) 1.0 x 10-9 meter
• 1 angstrom (A) 1.0 x 10-10 meter

o
o
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Temperature Scales

• Fahrenheit
• Celsius
• Kelvin

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Temperature Scales
Celsius
Kelvin
Fahrenheit


100 C
373 K
212 F
Boiling point of water
100 K
180F
100C
Freezing point of water
0C
273 K
32F
Notice that 1 K degree 1 degree Celsius
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Temperature Scales
100 oF 38 oC 311 K
32 oF 0 oC 273 K
Conversion Factor 100 oC degrees per 180 oF
degrees
oF
K
oC
38 oC (100 oF 32 oF) 100 oC / 180 oF 311 K
273 K 38 oC 100 K / 100 oC
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Calculations Using Temperature

• Generally require temps in kelvins
• T (K) t (C) 273.15
• Body temp 37 C 273 310 K
• Liquid nitrogen -196 C 273 77 K

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Physical Properties
sodium

• What are some physical properties?
• color
• melting and boiling point
• odor

salt
Physical properties characterize the identity of
pure substances
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Physical Changes

• Some physical changes would be
• boiling of a liquid
• melting of a solid
• dissolving a solid in a liquid to give a
  homogeneous mixture a SOLUTION.

Physical changes do not change the identity of
Pure Substances
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DENSITY - an important and useful physical
property
Physical properties, contd
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3
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• Problem A piece of copper has a mass of 57.54 g.
  It is 9.36 cm long, 7.23 cm wide, and 0.95 mm
  thick. Calculate density (g/cm3).

mass
(
g
)

Density

3
volume
(
cm
)
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• Strategy
• 1. Get dimensions in common units.
• 2. Calculate volume in cubic centimeters.
• 3. Calculate the density.

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Conversion factor

• SOLUTION
• 1. Get dimensions in common units.
• 2. Calculate volume in cubic centimeters.
• 3. Calculate the density.

(9.36 cm)(7.23 cm)(0.095 cm) 6.4 cm3
Note only 2 significant figures in the answer!
Significant Figures ??!!! of digits, starting
from the left, with the first digit different
from zero. (Trailing zeros dont count)
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Significant Figures
57.54 g 4 significant figures 7.23 cm
3 significant figures 0.95 mm 2 significant
figures 0.095 cm 2 significant figures
(zeros to the left of 9 simply
locate the decimal point) 600. g
3 significant figure 8000 kg 1
significant figure 100 cm/m infinte number of
significant figures (defined
quantity)
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DENSITY

• Density is an INTENSIVE property of matter.
• does NOT depend on quantity of matter.
• temperature
• Contrast with EXTENSIVE
• depends on quantity of matter.
• mass and volume.

Brick
Styrofoam
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INVERSE PROBLEM Mercury (Hg) has a density of
13.6 g/cm3. What is the mass of 95 mL of Hg in
grams? In pounds?
Solve the problem using DIMENSIONAL ANALYSIS.
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PROBLEM Mercury (Hg) has a density of 13.6
g/cm3. What is the mass of 95 mL of Hg?
First, note that 1 cm3 1 mL

• Strategy
• 1. Use density to calc. mass (g) from volume.
• 2. Convert mass (g) to mass (lb)
• Need to know conversion factor
• 454 g / 1 lb

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PROBLEM Mercury (Hg) has a density of 13.6
g/cm3. What is the mass of 95 mL of Hg?
Inverse Problems

• 1. Convert volume to mass

2. Convert mass (g) to mass (lb)