Calibration, Temperature & Percent Error
description
Transcript of Calibration, Temperature & Percent Error
Calibration, Temperature & Percent Error
What is Calibration?
Calibration of any measuring device is: distance between two two closest linesclosest lines
(NNotot distance between two closest #’s!)
Not all graduated cylinders calibrated same way
Large graduated cylinder:
? ? capacitycapacity
?? calibration calibration
1000 1000 mlml
10 ml10 ml
? calibration ? calibration 1 ml1 ml
? calibration ? calibration 1 ml1 ml
? calibration ? calibration 0.2 ml
Here are some other pieces of lab equipment.
Can you figure the calibration of each?
meter stick: two closest lines are 1 millimeter apart
? calibration? calibration
25 ml25 ml
This is a quadruple beam balance
What’s the calibration?
0.01 gram
This is a buret
? calibration
0.1 ml0.1 ml
Note: unlike graduated cylinder, numbers go down, so you read downwards
TemperatureScales
Scientifically speaking …
The definition of temperature:
Temperature is measure of average kinetic energy of particles in system
World’s Record Cold Temperatures
Date ˚F ˚C
World (Antarctica): Vostok II 7/21/1983 –129 –89Verkhoyansk, Russia(Siberia) 2/7/1892 –94 –70Asia: Oimekon, Russia 2/6/1933 –90 –68Greenland: Northice 1/9/1954 –87 –66No A: Snag, Yukon, Canada 2/3/1947 –81 –63US: Prospect Creek, Alaska 1/23/1971 –80 –62US: (other than AK) Rogers Pass, Mont. 1/20/1954 –70 –56.5
Conversion formulas
How can we convert from one temperature scale to another?
K = °C + 273 (more precisely 273.15)
°C = K – 273
[F = (9/5 °C) + 32]
Errors are inevitable and need to be dealt with …
Percent Error
Ratio of error to accepted value
% error = Error x 100%
accepted value
Error
measured value – accepted value x100% accepted value
absolute value: always positiveabsolute value: always positive
Data tableData table
1.711.451.57Trial 3
1.691.681.60Trial 2
1.701.401.54Trial 1
Student C
(g/cm3)
Student B
(g/cm3)
Student A
(g/cm3)
Students asked to find density of sucrose [Sucrose has density of 1.59 g/cm3]
LetLet’’s calculate the errors calculate the error
0.120.140.02Trial 3
0.100.090.01Trial 2
0.110.190.05Trial 1
Student C
(g/cm3)
Student B
(g/cm3)
Student A
(g/cm3)
Remember, error is always positive numberRemember, error is always positive number
Now letNow let’’s calculate % errors calculate % error
7.58.81.26Trial 3
6.35.70.63Trial 2
6.911.93.14Trial 1
Student C
error
Student B
error
Student A
% error
Advantage of % Error
•easier to compare data, especially if comparing data from different trials