Download Data Analysis

Data Analysis
Applying Mathematical
Concepts to Chemistry
Units of Measure

SI Units- scientifically
accepted units of
measure:
The Metric System
Metric Practice
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623.19 hL = __________ L
1026 mm = ___________cm
0.025 kg = ___________mg
Online Powers of 10 Demonstration:
http://micro.magnet.fsu.edu/primer/java/science
opticsu/powersof10/
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Derived Quantities- Volume
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Volume- amount of
space an object takes
up.
V = l x w x h (all in
meters)
V= m3
m3 is too large so cm3
are used
1 cm3 = 1 mL by
definition
Temperature Scales
Temperature Conversions

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Degrees Celsius to
Kelvin
Tkelvin=Tcelsius + 273
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Kelvin to Degrees
Celsius
Tcelsius=Tkelvin - 273
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EX: 25 °C = ? K
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EX: 210 K = ? °C
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Tkelvin=25 +273=298K
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Tc= 273–210= -63°C
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Scientific Notation
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A method of expressing very large or small
numbers in a concise manner
Requires 2 parts:
–
Number between 1 and 9.99999999…
Power of ten
–
EX: 5432.1 meters 5.4321 x 103 meters
–
Factor Labeling (Dimensional
Analysis)
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Any number divided by itself is equal to 1
–
–
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6/6 = 1
6 meters/6 meters = 1
Any number can be multiplied by one without
changing its value
–
–
5 x (6/6) = 5
5 x (6 meters/6 meters) = 5
Converting Units Through
Dimensional Analysis
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Equal units divided by one another are equal
to 1
1m/100 cm = 1 m/cm
100 cm/1m = 1 cm/m
50 cm x (1m/100cm) = 0.5 m
50 m x (100cm/1m) = 5000 cm
Practice Problems

12.5 eggs = ? Dozen
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13.69 m = ? cm
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13.69 km = ? cm
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1.25 x 103 ft = ? yd
Multiple Step Factor Labeling
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5.2 x103 yd = ? In
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45 mph = ? ft/min
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3.1 g/mL = ? Kg/L
Derived Quantities- Density
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Density- how much matter is in the volume an object
takes up.
Density = mass/volume
D= g/mL
Determining Density

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Mass- measure in grams with balance
Volume–
Regular shaped object: measure sides and use
volume formula

–
EX: rectangle  V= l x w x h
Irregular shaped object: water displacement
Density by Water Displacement
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Fill graduated cylinder
to known initial volume
Add object
Record final volume
Subtract initial volume
from final volume
Record volume of
object
Graphing Data
How Does Volume Impact Temperature?
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General Rules
–
–
–
–
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Fit page
Even scale
Best fit/trendline
Informative Title
Labeled Axes
Accuracy vs Precision
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Accuracy- closeness of
measurements to the
target value
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Precision- closeness of
measurements to each
other
Percent Error

%error = (accepted-experimental) x 100
accepted

EX: The measured mass is 5.0g. It was
predicted that the accepted value should
have been 6.0 g.
% error = 6.0g-5.0g x 100 = 16.7%
6.0g
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Significant Figures
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Measurements are
limited in their
sensitivity by the
instrument used to
measure
Estimating Measurements

Read one place past
the instrument
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35.0 mL is saying the
actual measurement is
between
34.9
and 35.1 mL
Why Significant Figures?
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Measurements involve rounding
Multiplying/dividing or adding/subtracting
measurements can not make them more
accurate
Provide a way to tell how sensitive a
measurement really is…
5 ≠ 5.0 ≠ 5.00 ≠ 5.000
Recognizing Significant Digits
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1. Nonzero digits are always significant
–
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2. Zeros between nonzeros are significant
–
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543.21 meters has 5 significant figures
505.05 liters has 5 sig figs
3. Zeros to the right of a decimal and a
nonzero are significant
–
3.10 has 3 sig figs
Recognizing Sig Figs
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4. Placeholder zeros are not significant
–
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–
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0.01g has one sig fig
1000g has one sig fig
1000.g has four sig figs
1000.0g has five sig figs
5. Counting numbers and constants have
infinite significant figures
–
5 people has infinite sig figs
Practice Identifying Sig Figs
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A) Clearly circle the significant digits in each of the
following numbers:
0.540 30 m
46.93 L
0.004 79 g
56.00 s
B) Rewrite each of the following numbers to the
number of significant digits which is specified in the
parenthesis:
0.012 70 (2)
2,190,050 L (2)
0.005 23 g (1)
3.079 s (2)
Rule for Multiplying/Dividing Sig
Figs
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Multiply as usual in calculator
Write answer
Round answer to same number of sig figs as
the lowest original operator
EX: 1000 x 123.456 = 123456 = 100000
EX: 1000. x 123.456 = 123456 = 123500
Practice Multiplying/Dividing
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50.20 x 1.500
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0.412 x 230
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1.2x108 / 2.4 x 10-7
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50400 / 61321
Rule for Adding/Subtracting
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Only place values where all measurements
being added/subtracted have sig figs are
utilized
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EX: 1002
+ 1.2345
1003
Practice Adding/Subtracting
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100.23 + 56.1
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.000954 + 5.0542
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1.2 x 104 – 5.02 x 103
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1.0045 + 0.0250