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CHEM 131- Final Exam Guide - Comprehensive Notes for the exam ( 62 pages long!)


Department
Chemistry and Biochemistry
Course Code
CHEM 131
Professor
Papoian
Study Guide
Final

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UMD
CHEM 131
Final EXAM
STUDY GUIDE

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Chemistry Chapter E: Units, Measurements, and
Problem Solving
The Units of Measurement:
Units are critical
Common systems: Metric System and English system
o Scientists use SI (based on metric)
Standard Units:
o Length = meter (m)
o Mass = kilogram (kg)
o Time = second (s)
o Temperature = kelvin (K)
Celsius, Fahrenheit, Kelvin
C = (F 32) / 1.8
K = C + 273.15
o Amount of Substance = Mole (mol)
o Electric Current = Ampere (A)
o Luminous Intensity = Candela (cd)
Units of Volume = cm^3, m^3, mm^3
Units of Densities = g/cm^3
Precision and Accuracy:
Accuracy how close the measured value is to the actual
value
Precision how close a series of measurements are to
another or how reproducible they are
o Inaccurate and imprecise inconsistency is the result
of random error
Random Error error that has the probability of
being too high or too low
o Inaccurate, but precise inconsistency is result of
systematic error
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Systematic Error error that tends toward being
too high or too low
Significant Figures Rules:
1. All nonzero digits are significant
2. Interior zeroes are significant
3. Leading zeroes aren’t significant. They only serve to locate
the decimal place
4. Trailing zeroes are categorized as follows:
a. Trailing zeroes after a decimal point are always
significant (45.000 = 5)
b. Trailing zeroes before a decimal point are always
significant (140.00 = 5)
c. Trailing zeroes before an implied decimal point are
ambiguous and should be avoided by using scientific
notation (1200 = ambiguous, 1.2 *10^3 = 2)
Exact Numbers:
Exact Numbers have no uncertainty and don’t limit the
number of significant figures in any calculations
o Has an unlimited number of significant figures
Originate from 3 sources:
o 1. Accurate counting of discrete objects
14 pencils = 14.00000 pencils
3 atoms = 3.000 atoms
o 2. Defined quantities
100cm = 1m = 100.000 cm
o 3. Integral numbers that are part of an equation
Radius = diameter / 2 … (2 is exact)
Significant Figures in Calculations:
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