che-108 chemistry lab instructor: robert goldman
TRANSCRIPT
CHE-108Chemistry Lab
Instructor: Robert Goldman
Today in lab…
Experiment #1 – Introduction & Physical Properties
Experiment and lab exercises done in class
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”
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-32ºC=(5/9) 212 ºF-32ºC=(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
10mm in 1cm
100cm in 1m
1000m in 1km
100ųL in 1mL
1000mL in 1L
100ųg in 1g
1000g in 1kg
Interconverting Metric Units
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
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…
1,300,000Or… 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!