Chapter 2-1 Method, Measurement &
Problem Solving Notesheets
Name _________________________
Period _____ Date_______________
I. What is Chemistry?
A. Chemistry is the study of all ______________ and the _________________ it can undergo.
B. Chemistry has been called the ______________ science because it overlaps so many sciences.
C. Chemical – any substance with a __________________ composition.
II. The Scientific Method: (2.2)
A. A ___________________ approach to gather knowledge.
B. Steps to the Scientific Method:
1. _______________________
2. ________________________
3. ________________________
4. ________________________
5. ________________________
*Note: All hypotheses must be able to be ______________ in order to be a true hypothesis.
C. Many Experiments
(
Natural Law
) (
Theory
)
III. Scientific Notation: Shorthand way of expressing very _____________ or very ___________ numbers.
(2.3)
A. Power of 10
Equivalent #
Reason
100
101
102
103
105
10-1
10-3
10-5
_________
_________
_________
_________
_________
_________
_________
_________
______________________________
______________________________
______________________________
______________________________
______________________________
______________________________
______________________________
______________________________
B. Express Numbers in Scientific Notation – move the decimal point so that there is only ____ nonzero digit to the left of the decimal point. Moving the decimal point left the power will be ____,
right the power will be ___.
1
1) 2700
________________
2) 0.0035
________________________
3) 2,640,000,000
________________
4) 0.010
________________________
C. Express Numbers in regular form – reverse the process.
5) 8.65 x 106 ______________________
6) 9.73 x 10-8 ________________________
D. Know how to use scientific notation in your calculator – different for graphing + scientific!
Ex. #7) 8.08 x 10-5 – 2.07 x 10-6 =
Ex. #8) 3.7 x 102
Ex. #9)
x
5.1 x 103 =
2.3 x 10-3
=
4.6 x 10-7
IV. Metric System: (1.2)
A. International System of Measurements (SI): standard system used by all scientists. It is based
upon multiples of ______.
B. Metric Units used in chemistry:
Measurement
Equation
Derived Unit
mass
----------
---------
length
----------
---------
time
----------
---------
temperature
----------
---------
----------
---------
quantity
Unit
Instrument
--------------------
area
volume
density
--------------------
pressure
energy
---------2
C. Prefixes
Prefix
teragigamegakilohectodekaBASE UNIT
decicentimillimicronanopico-
Abbreviation
Meaning
--------------
1
Scientific Notation
D. Metric Conversions using the Factor-Label Method (Dimensional Analysis)
Ex. #1) Convert $72 to quarters:
4 quarters
72 dollars
1 dollar
Ex. #2) Convert 15 g to kg
Ex. #3) Convert 20 mL to kL
Ex. #4) Convert 0.071 m3 to Liters
Ex. #5) Convert 25 L to m3
Ex. #6) The wavelength of blue light is 450 nm convert to pm
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V. Uncertainty in Measurement: (2.3)
A. Measurements are uncertain because:
1. Instruments are not free from __________________.
2. Measuring always involves some _____________________.
B. Estimating with a scale
1. Estimate ______ digit more than the instrument measures
2. is used to show _____________________which is the last ____________________digit.
C. Precision: When the instrument gives you about the ____________ results under
similar conditions.
D. Accuracy: When the experimental value is close to the ____________ value. The____________
the increments of measurement an instrument has, the more accurate it can be.
E. An instrument is ________________ (numbers repeatable to a certain number of places) the
operator makes it _____________________ (close to the right answer by using it correctly).
Ex. Precise, Accurate, Both or Neither
(Accepted Value = 15g)
1. 200g, 1g, 40g _____________________________
2. 78g, 80.g, 79g _____________________________
3. 16g, 14g, 17g _____________________________
F. Dartboard Analogy:
VI. Significant Digits
A. Significant Digits include ___________________ digits and ___________________ digits.
Use Atlantic-Pacific Rule for determining number of significant digits – see map handout.
B. Addition and Subtraction
1. Add or Subtract numbers.
2. Round answer to the least precise piece of equipment (look at __________ places.)
Ex.
951.0 g
1407
g
23.911g
158.18 g +
4
B. Multiplication and Division
1. Multiply or Divide numbers.
2. Round answer to the least _________________ of significant digits.
Ex. #1)
7.079 cm
=
0.535 cm
Ex. #2) V = L x W x H
V= 3.05 m x 2.10 m x 0.75 m =
Ex. #3) A = L x W
A= 3200 cm x 2500 cm =
VII. Important Formulas:
A. Percent Error: Comparing a measurement obtained experimentally with an _________________
value. It is always expressed as a __________________ %.
% error =
measured value - accepted value
x 100% =
accepted value
Ex.) If a student calculates the density of aluminum to be 2.5 g/cm3, and the accepted value is
2.702 g/cm3, what was her % error?
B. Density =
Mass
Volume
M=
V=
Ex.) If a metal block has a mass of 75.355 g and a volume of 22 cm3, what is the density?
Ex.) Determine the volume of 23.249 g of nail polish remover (acetone - density of 0.791 g/mL)
5
VIII. Dimensional Analysis (The Factor-Label Method):
A. Uses unit equalities to convert between ________________. A unit equality is an equation that
_______________ 2 units.
Ex.) 12in = 1 ft
60sec = 1 min
1kg = 1000 g
B. Unit equalities are used to write __________________ ________________ which are always
equal to “1.”
Ex)
1000 m
=1
1 km
or
1 km
=1
1000 m
C. The conversion factor is a definition, and therefore infinitely precise, so the number of significant
digits in the answer is equal to the number in the ___________which is the _____________ value.
Useful Chemistry Conversion Factors
1 in. = 2.54 cm
1 atm = 760 mm Hg
1 ft. = 12 in.
1 atm = 101,325 Pa
1 mile = 5280 ft.
1 cal. = 4.184 J
1 min. = 60 s
1 Cal = 1000 cal
1 hr. = 60 min.
1 gal. = 3.785 L
Ex. #1) How many seconds are in 22 hours?
Ex. #2) How many years are 3 x 108 seconds?
Ex. #3) If there are 9 dibs in 1 sob, 3 sobs in 1 tog, 1 tog in 6 pons, and 12 pons in 1 gob. How many
gobs are in 27 dibs?
Ex. #4) Calculate the number of feet in a 5.00 km race. (1 inch = 2.54 cm)
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