1. MEASURMENT, PERCENT ERROR, AND ACCURACY VS. PRECISION

2. DETERMINING: MASS & VOLUME

3. MASS Turn this knob to make sure balance is zeroed Tenths place Ones place Tens place Hundreds place

4. 100200300400500 102030405060708090 100 123456789 10 100200300400500 102030405060708090 100 123456789 10 100200300400500 102030405060708090 100 123456789 10 100200300400500 102030405060708090 100 123456789 10 140.5 g 74.8 g 500 g

5. 30 40 VOLUME GRADUATED CYLINDER VS. BURET MEASURES THE VOLUME OF A LIQUID What is this called? The meniscus! 33.5 mL MEASURES THE VOLUME OF A LIQUID RELEASED (USED IN TITRATIONS) 50 40 4.00 mL

6. PERCENT ERROR Your Measured Value – Actual Value Actual Value X 100 Absolute Value sign: the difference cannot be negative

7. Making sure you subtract the mass of the box, you re-measure the mouse and determine its real mass as 15.0 grams. What is the percent error? Example: You measure the mass of a mouse to be 14.6 grams. But because it is constantly jumping around you are not sure if you made an accurate measurement. SO: *No real mice were hurt in this example.

8. - 0.4g 15.0g CALCULATION 14.6g -15.0g 0.0267 x 100 == 2.67% error Measured Value – Actual Value Actual Value X 100

9. ACCURACYPRECISIONvs. Average is close to the actual number/value Grouped close together (small range)

10. ACCURACYPRECISIONvs.

11. ACCURACYPRECISIONvs.

12. Accurate, Precise or Neither 5.1 5.2 5.0 417 638 962 13.2412.9913.15 Accepted Value: 5.14 Accepted Value: 10.25 Accepted Value: 947 Trial 1Trial 2Trial 3 20.115.926.8 20.313.427.4 19.923.027.2 Accepted Value: 27.3 A P N PAPN P

13. 10 20 30 40 50 60 70 80 90 100 A B C D E

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