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CHEM 1151 Guided Notes
Chapter 2 Chemistry and Measurements
Vocab to Know!
•
Celsius (°C) temperature
scale
•
centimeter
•
conversion factor
•
cubic centimeter (cm
3
, cc)
•
density
•
equality
•
exact number
•
gram (g)
•
international system of units
(SI)
•
kelvin (k) temperature scale
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kilogram (kg)
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liter (L)
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mass
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measured number
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meter (m)
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metric system
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milliliter (mL)
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prefix
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second (s)
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significant figures (SFs, sig
figs)
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temperature
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volume
2.1 Units of Measurement
Learning Goal
Write the names and abbreviations for the metric or SI units used in measurements of length,
volume, mass, temperature, and time.
Units of Measurement
Scientists use the
_______________ ________________
of measurement
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adopted a modification of the metric system called the
________________ __________________ ____
______________________
as a worldwide standard.
✓
an official system of measurement used throughout the world for units of length, volume, mass,
temperature, and time.
Length: Meter (m) and Centimeter (cm)
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is measured using a meter stick.
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uses the unit _________________ in both the metric and SI systems.
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uses _________________________________ for smaller units of length.
Volume: Liter (L) and Milliliter (mL)
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is the _________________ occupied by a substance.
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uses the __________________________ in the metric system.
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Graduated cylinders are used to measure small volumes.
Chapter 2 Preview
2.1 Units of Measurement
2.2 Measured Numbers and
Significant Figures
2.3 Significant Figures in
Calculations
2.4 Prefixes and Equalities
2.5 Writing Conversion Factors
2.6 Problem Solving Using Unit
Conversion
2.7 Density
1 m =
1 m =
1 m =
2.54 cm =
1 L
=
1 L
=
946 mL
=

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Mass: Gram (g) and Kilogram (kg)
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a measure of the quantity of material it contains.
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measured in grams (g) for small masses.
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The mass of a nickel is 5.01 g on an electronic scale.
Temperature: Celsius (
°
C) and Kelvin (K)
•
Water freezes:
✓
32 °F
✓
0 ° C
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The Kelvin scale for temperature begins at the lowest possible temperature, 0 K.
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A thermometer is used to measure temperature.
Time: Second (s)
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The second (s) is the correct metric and SI unit for time.
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The standard measure for 1 s is an atomic clock.
Study Check
Identify the SI units for each of the following:
A.
The SI unit for volume is the_____________________________________
B.
The SI unit for mass is the _______________________________________
C.
The SI unit for length is the ______________________________________
D.
The SI unit for temperature is the _________________________________
2.2 Measured Numbers and Significant Figures
Learning Goal
Identify a number as measured or exact; determine the number of significant figures in a
measured number.
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Length is measured by observing the marked lines at the end of a ruler.
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The last digit in your measurement is an ______________________, obtained by visually dividing the
space between the marked lines.
Measured Numbers
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Measured numbers
are the numbers obtained when you measure a quantity such as your height,
weight, or temperature.
•
To write a
measured number
,
1.
observe the numerical values of marked lines
2.
estimate value of the numbers between marks
3.
use the
estimated number
as the final number in your measured number
1 kg
=
1 kg
=
454 g
=
1 day =
1 h
=
1 min
=