Transcript Scientific Measurement:

Scientific Measurement
Chapter 3
Qualitative and Quantitative
Measurement:
Qualitative measurement:
Results are descriptive
Results are in non- numerical
form
(Quality)
Many, fuzzy, blue
Qualitative and Quantitative
Measurement:
Quantitative measurement:
Results are in definite form
Results are given in number
and units
(Quantity)
6 mL, 38 mph, 5 feet tall
Accuracy, Precision, Error
What do we mean by
accuracy?
A measurement of how close
a measurement comes to the
actual or true value of what
ever is measured.
Accuracy, Precision, Error
How about precision?
A measure of how close a
series of measurements
are to one another.
Accuracy, Precision, Error
What is error?
The difference between
accepted and
experimental values.
% error
To calculate % error, use
the following equation:
Accepted – experimental value x 100%
accepted value
Units of Measurement:
SI (International System of
Units)
Quantity
Length
Time
Mass
Temperature
Amount of substance
Energy
Unit
Meter (m)
Second (s)
Kilogram (kg)
Kelvin (K)
Mole (mol)
Joule (J)
Scientific Notation
In science, we deal with very small
and very large numbers:
1 mole= 602000000000000000000000
Mass of electron=
0.0000000000000000000000000000000
91 kg
Scientific Notation
A method of representing very large
of small numbers in the form:
M x 10n
Where:
M is a number between 1 and 9.9
n is an integer
.
2 500 000 000
9 8 7 6 5 4 3 2 1
Step #1: Insert an understood decimal point
Step #2: Decide where the decimal must end
up so that one number is to its left
Step #3: Count how many places you bounce
the decimal point
Step #4: Re-write in the form M x 10n
2.5 x
9
10
The exponent is the
number of places we
moved the decimal.
0.0000579
1 2 3 4 5
Step #2: Decide where the decimal must end
up so that one number is to its left
Step #3: Count how many places you bounce
the decimal point
Step #4: Re-write in the form M x 10n
5.79 x
-5
10
The exponent is negative
because the number we
started with was less
than 1.
Practice
159302
900024
0.000426
0.002