3 Can you hit the bull's-eye? Three shooters with three arrows each to shoot.How do they compare?Both accurate and precisePrecise but not accurateNeither accurate nor precise
4 Measure the diameter of the ball Using a metric stick, determine the diameter of the ball provided.Compare your results with another group.Any problems with your measurement?
5 Can all errors be controlled? What are some possible things that can be done to minimize errors?
6 Types of (experimental) Errors Systematic Error Result of an experimental “mistake”Sometimes called bias due to error in one direction- high or lowPenyebabnya diketahui (known cause)OperatorCalibration of glassware, sensor, or instrument, etc.
7 Types of (experimental) Errors Systematic ErrorThis error can be corrected/ controlled when causes of error are determined, i.e :(a) calibrating all experimental tools and/or instruments(b) controlling skill of experimenter,operator etc.(c) Cleaning all glassware, bottles, etcbefore doing experiments(d) etc… ?????
8 Types of (experimental) Errors Systematic ErrorTypically produce constant or proportional nature (slowly varying bias)y = ax + bProportional error influences the slope.Constant error influences the intercept.
9 Types of (experimental) Errors Random errorUnpredictable, non-deterministicUnbiased → equal probability of increasing or decreasing measured valueResult ofLimitations of measuring toolRandom processes within systemEnvironmental effect (?), etcTypically cannot be controlledUse statistical tools to characterize and quantifyMultiple trials help to minimize
16 Systematic errors → accuracy How close mean of measured values is to true valueRandom errors → precisionRepeatability/reproducibility of measurementsCharacteristics of tools → resolutionSmallest increment between measured values
17 Most accurate and precise Graphical methodsScatter plotsMost accurate and preciseSystematic error?Worst precision
18 Two students analyzing two different CaCO3 antacid tablets True valueStudent 1Student 2Label value500 mg750 mgMean463 mg761 mgStd. dev.20 mg28 mgWhich student has the more accurate results?Which student has the greater precision?
19 How are we going to address these questions? quantityStudent 1Student 2% Relative standard deviation asses the precision%Error asses the accuracy
20 calibration marks + one more place Always remember to…Make all measurements carefully and check your results or readings a second time.Read all devices to as many places as possible (significant figures):calibration marks + one more placeA buret, which is calibrated to 0.1 mL, can be read to 0.01 mL.A thermometer marked every degree can be read to 0.1 degree
21 Kandungan rhodamin dalam sampel Metode Spektrofotometri Metode ESIMetode SpektrofotometriUlangan123Saos A0.110.250.150.100.17Saos B0.220.340.320.38Berapakah konsentrasi rhodamin pada saos A dan B yang terukur dengan metode ESI dan spektrofotometri?Berapakah ketelitian dan ketepatan pengukuran rhodamin dengan kedua metode jika konsentrasi rhodamin sebenarnya dalam saos A 0.18 ppm dan saos B 0.24 ppm?Apa saja sumber systematic dan random errors dalam pengukuran tersebut?