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Processing Lab Data

Processing Lab Data. Mrs. Page 2014-2015. After Collecting Data = Process Data. Raw Data: the data you collect during lab without any calculations Qualitative Data: Descriptive data – observed with senses, (i.e. what does it look like, sound like, feel like)

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Processing Lab Data

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  1. Processing Lab Data Mrs. Page 2014-2015

  2. After Collecting Data = Process Data • Raw Data:the data you collect during lab without any calculations • Qualitative Data:Descriptive data – observed with senses, (i.e. what does it look like, sound like, feel like) • Quantitative Data:Measured data using tools. Will be number values. • Processed Data:data as a result of performing calculations AFTER all data has been collected • Raw Data & Processed Data are kept on SEPARATE DATA TABLES!!!

  3. DENSITY • Density is a physical property of matter • Density refers to how tightly packed the particles are in an object • Tightly packed = more dense • Loosely packed = less dense • or • Units for density are or (note:

  4. Practice Calculating Density • If you measure an object that has a mass of 8.47 g and a volume of 3.1 cm3. Calculate the density of the object. Remember Sig. Fig. Rules

  5. YOU TRY • What is the density of an 84.70 g sample of an unknown substance if the sample occupies 49.6 mL? • What volume would be occupied by 7.75 g of the same substance? (Use the density from the first problem)

  6. Accuracy vs. Precision • Accuracy: how close a measurement is to an accepted value (literature value) • Precision: how close the measurements are to each other

  7. Percentage Error • You can determine how accurate your data is by calculating the percentage error • The larger the percentage error, the more inaccurate your data is • The smaller the percentage error, the more accurate and reliable your results are. • Note: error can be positive or negative, this just means your values are higher or lower than the accepted value

  8. Practice Calculating Percentage Error • What is the percentage error for a mass measurement of 17.8 g, given that the correct value is 21.2 g? Remember Sig. Fig. Rules

  9. YOU TRY… • A volume is measured experimentally as 4.26 mL. What is the percentage error, given that the correct value is 4.15 mL? • A student measures the mass and volume of a substance and calculates its density as 1.40 g/mL. The correct, accepted, value of the density is 1.30 g/mL. What is the percentage error of the student’s measurement?

  10. Experimental Errors • 2 Types: Random & Systematic • Random Errors: unpredictable, chance variations that experimenter has little control over– using many trials and averaging results helps alleviate this type of error. (ex: parallax error) • Systematic Errors: caused by the way in which the experiment was conducted (design). Systematic errors can not be eliminated by averaging. Must change how experiment is conducted. (ex: not calibrating instruments) • Human Error: should not occur if you are focused and careful

  11. HOMEWORK • Read/review pages 44-57 in your textbook. • Complete questions 1-8 on page 57. SHOW ALL WORK.

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