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