Transcript Chemistry Lab 108-50 Summer I 2006

CHE-108
Chemistry Lab
Instructor: Robert Goldman
Today in lab…
Experiment #1 – Introduction & Physical
Properties
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Experiment and lab exercises done in class
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Homework #1 completed and turned in next
week – DUE AT START OF CLASS
Experiment #1
Chemistry: the science of matter; the branch of
the natural sciences dealing with the
composition of substances and their properties
and reactions
Experiment #1
What is matter?
Anything that has mass and occupies space
The atom is the smallest indivisible unit of
matter!
Experiment #1
What is mass?
The amount of matter present in a sample.
MASS IS CONSTANT!!
Experiment #1
Mass vs. Weight?
Technical definition of weight:
“the vertical force exerted by a mass as a result of
gravity”
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Weight is NOT constant
Defined by relationship of mass and gravity.
–
Ex: you WEIGH less on the moon (less gravity) but
your MASS is the same.
Experiment #1
What is a chemical property?
Property that changes in a reaction
Ex: Rust formation on iron due to oxidation, ability of
wood to burn.
You can’t “un-rust” metal or “un-burn” wood!
Experiment #1
What is a physical property?
A property that can be observed without changing the
chemical composition of the sample.
Ex: Color, shape, mass, volume, ability to
dissolve: You CAN “un-dissolve” salt!
Experiment #1
You can use a samples chemical and physical
properties to separate different components of
a solution.
For example, a mixture of sand and sugar can be
separated in water:
Sand sinks to bottom, sugar dissolves.
Pour off water, evaporate water, sugar is left.
Experiment #1
What is density?
“Mass per unit volume”
Ex: the density of H20 is 1g/mL
So… 10mL of H20 is how many g?
Experiment #1
Relationship of Mass, Volume, and Density
Density=Mass/Volume (D=M/V)
If the density of H20 is 1g/mL and the volume is 10mL…
1g/mL=M/10mL
We can solve for M and arrive at 10g!
Experiment #1
Rearranging the density equation:
D=M / V
M=D x V
V=M / D
Experiment #1
In science, we use the METRIC SYSTEM
Temperature: ºC vs. ºF
Volume: liters vs. gallons
Length: meters vs. yards
Mass: grams vs. ounces
Always include these units in calculations!
Experiment #1
It is important to be able to convert between
english and metric units.
The boiling point for water is 212 ºF, what is the
B.P. in ºC?
Experiment #1
Temperature conversions
212 ºF to ºC
ºC=(5/9) º F-32
ºC=(5/9) 212 ºF-32
ºC=(5/9) (180)
ºC=100 ºC
Experiment #1
Temperature conversions
Water freezes at 0 ºC, how about in ºF?
ºF=(9/5) ºC + 32
ºF=[(9/5) 0ºC] +32
ºF=(0) + 32
ºF=32 º freezing temperature
Experiment #1
Interconverting Metric Units
10mm in 1cm 100ųL in 1mL
100cm in 1m 1000mL in 1L
1000m in 1km
100ųg in 1g
1000g in 1kg
Experiment #1
What is energy?
Technically: the capacity for doing work.
Forms: thermal, mechanical, electrical, and
chemical.
Experiment #1
LAW OF CONSERVATION OF ENERGY
AKA First Law of Thermodynamics
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ENERGY IS NEVER CREATED OR DESTROYED!
It may, however, be transformed from one form into
another.
The amount of energy in the universe is constant.
Experiment #1
LAW OF CONSERVATION OF MASS/MATTER
AKA -Lavoisier Law
Mass can be neither created nor destroyed
during a chemical reaction- only changed from
one form to another.
Experiment #1
Scientific Notation
… a method for “compacting” very large or small
numbers.
Ex: 1.3 x 106 or 3.2 x 10-2
Experiment #1
Scientific Notation
1.3x106
Move the decimal point to the RIGHT (+) six
places…
1,300,000
Or… take out the decimal and add 5 0’s after the
number
Experiment #1
Scientific Notation
3.2x10-2
Move the decimal point to the LEFT (-) two places…
0.032
Or… take out the decimal and add one 0 before the
number
(The zero before the decimal isn’t ESSENTIAL, but it is
helpful…)
Experiment #1
For today’s lab…
 Follow directions outlined in lab manual.
 Record results on worksheets- NOT IN BOOK.
 ASK QUESTIONS!