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

4. Practice Calculating Density  If you measure an object that has a mass of 8.47 g and a volume of 3.1 cm 3. 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

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.