Calibration, Temperature & Percent Error

What is Calibration? two closest lines calibration of any measuring device is: distance between two closest lines NOT NOT distance between two closest #’s NOT all same instruments calibrated the same

not all graduated cylinders calibrated same way

Large graduated cylinder: ? capacity ? calibration 1000 ml 10 ml

? calibration 1 ml 67.4 ml meniscus falls between 67ml & 68ml

? calibration 1 ml 13.0 ml what about: 12.9 ml 13.1 ml ? ?

Can you figure the calibration of any piece of lab equipment? YES

meter stick: two closest lines are 1 mm (millimeter) apart

? calibration 25 ml

quadruple beam balance

What’s the calibration? 0.01 g g g g

meniscus between 21.3ml & 22.4ml ? calibration 0.1 ml BURET: unlike graduated cylinder, numbers go down, so you read backwards compared to way read graduated cylinder ml

Temperature Scales

scientifically speaking … the definition of temperature: temperature is measure of average kinetic energy of particles in system

comparing 3 different scales comparing 3 different temperature scales

World’s Record Cold Temperatures Date ˚F ˚C World : East Antarctica 8/2010 –135.8 –94.7 Verkhoyansk, Russia(Siberia) 2/7/1892 –94 –70 Asia: Oimekon, Russia 2/6/1933 –90 –68 Greenland: Northice 1/9/1954 –103 –75 No. America: Snag, Yukon, Canada 2/3/1947 –81 –63 US: Prospect Creek, Alaska 1/23/1971 –80 –62 Rogers Pass, Montana 1/20/1954 –70 –56.5

Conversion formulas To convert between celsius & Kelvin scales: K = °C (more precisely ) °C = K – 273 [F = (9/5 °C) + 32]

errors in science experiments are inevitable and need to be dealt with …

Percent Error ratio of error to accepted value % error = error x 100 accepted value

Calculation of Error     measured value – accepted value  x 100 accepted value absolute value: always positive

Data table Trial Trial Trial 1 Student C (g/cm 3 ) Student B (g/cm 3 ) Student A (g/cm 3 ) students asked to find density of sucrose [sucrose has density of 1.59 g/cm 3 ]

calc differences in density Trial Trial Trial 1 Student C (g/cm 3 ) Student B (g/cm 3 ) Student A (g/cm 3 ) Remember, error is always positive number

then calculate % error Trial Trial Trial 1 Student C % error Student B % error Student A % error

What can do with error? easy to compare data from one student/group to another easy to compare data from one trial to another can map change from one lab to next or from start of year to end