Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
Define ACCURACY:
Define PRECISION:
________________
________________
________________
________________
Four lab groups performed the same experiment three times to determine the melting point of
naphthalene (moth balls). The accepted melting point is 79.0°C. Indicate whether the following sets of
data are precise, accurate, both or neither.
Precise,
Accurate,
Both , or
Neither
Reasoning
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Group
Trial 1
Trial 2
Trial 3
1
76.2°C
79.5°C
81.3°C
2
76.2°C
76.1°C
76.3°C
3
86.4°C
82.8°C
81.2°C
4
79.1°C
78.9°C
79.2°C
Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
What is a QUALITATIVE measurement?
What is a QUANTITATIVE measurement?
Glassware
Qualitative or
Quantitative
Function
Beaker
Large mouth glass containers used to contain approximate
volumes of liquid
Buret
Long tube with a stopcock that opens and closes. It is used to
precisely deliver solutions, especially in a titration
Erlenmeyer
Flask
Glass container used to contain approximate volumes of liquid.
Small mouth accommodates a stopper for storage or shaking.
Graduated
Cylinder
Used to measure and deliver approximate volumes of liquids.
Pipet
Used to precisely deliver variable quantities of liquid.
Test Tube
Glass cylinder that holds liquids being tested in an experiment.
Volumetric
Flask
Designed to precisely contain a specific volume. Commonly used
when accurately making aqueous solutions.
MEASUREMENT & SIGNIFICANT FIGURES
Explain the process of making a detailed measurement.
How do you take measurements when a meniscus is present?
What is the difference between a buret & a graduated cylinder?
How can you tell which one you are working with?
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Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
MEASUREMENT & SIGNIFICANT FIGURES
C
A B
D
E
A:
C:
E:
B:
D:
F:
F
Read the graduated cylinder to the correct number of
significant figures.
A
B
A:
B:
Read the buret to the correct number of significant figures.
Then calculate the amount of fluid released.
Initial
10 mL
Initial Amount of fluid:
Final
Final amount of fluid:
20 mL
Amount of fluid released:
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Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
USING SIGNIFICANT FIGURES:
Significant figures indicate how much _________________ or
estimation of a measurement is known.
Write the four rules for using significant figures.
1)
Count and underline the significant
figures in each of the following
numbers.
1) 4000
2) 0.0045
3) 0.00909
4) 2.050x1024
5) 3.990
2)
6) 100.0
7) 1010
3)
8) 100.
Round to three significant figures.
1) 123,499
4)
2) -234,999
3) 0.231451
4) 18.99
MULTIPLICATION & DIVISION
In multiplication and division, the answer can
have no more significant figures than are in
the measurement with the ____________
number of significant figures.
_____________ numbers such as
_______________ numbers and
_____________________ are not included
when counting significant figures
Write how many significant figures would be in your
answer for the following equations.
Then solve each equation.
1) 0.006760 / 32
2) 1,234,000 / 0.0000345
3) 278.4 X 25.2
4) 89.554 X 43.1
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Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
SCIENTIFIC NOTATION
Convert to decimal form:
Scientific notation is used to represent numbers that are very large or
very small numbers.
1.1x103
When using scientific notation in the calculator you should use the EE
button.
1) To convert from decimal form to scientific notation:
-2.35x105
2) To convert from scientific notation to decimal form:
1.12x10-3
-2.35x10-5
Convert to scientific notation:
To correct scientific notation:
1) Move the decimal so that only one ________________ digit
remains to the left of the decimal
75,100,000
-234,900
2) Increase the exponent if:
0.00000231
3) Decrease the exponent if:
-0.00003549
ALGEBRAIC MANIPULATION:
Rearrange the equations on the right
to solve for the variable that is in bold:
D
m
V
D
m
V
DENSITY
Density is
What are the units for density?
What is the equation for density?
What is the density of water?
Under what circumstances will something sink in water?
1) Using information above, what is more dense, ice or liquid water?
2) A Certain solid has a volume of 35.7 cm3 and a mass of 85 g. What is its density?
3) The density of gold is 19.3 g/ml. What is the volume of 200 g of gold?
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Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
UNITS OF MEASUREMENT
Mass (m)
Prefix
Abbr.
Sci. not.
Temperature (T)
Giga
G
1×109
Volume (V)
Mega
M
1×106
Kilo
k
1×103
Wavelength (λ)
Hecto
h
1×102
Frequency (f)
Deca
da
1×101
Energy (E)
Deci
d
1×10-1
Centi
c
1×10-2
One hundredth of a gram =
Milli
m
1×10-3
One billionth of a liter =
Micro
μ
1×10-6
n
1×10-9
Amount (mol)
Write the abbreviations:
Nano
One tenth of a meter =
One thousand grams =
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Memorize highlighted ones
Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
DIMENSIONAL ANALYSIS
Dimensional analysis is a method of arranging conversion factors to convert
any unit to any other unit.
Write the steps for performing dimensional analysis below:
Example: How many hours
are there in 190.7 minutes?
1)
2)
1) Convert 378.4 cm to
meters
3)
4)
5)
2) Convert 4.32 X 10-4 g to
milligrams
6)
7)
8)
9)
To go from one side of the base unit to the other
side of the base unit, you must do a two step grid.
1) Convert 5.43 kL to dl
First convert to the base unit,
then convert from the base unit.
2) Convert 6.99x108 kg to cg
Example:
Convert 231 mm to km
Questions?? Be sure to write them down to ask in class!!
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Unit 1-B Student Notes - Data Collection & Analysis
General Chemistry
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