1. Index Measured Values Conversion Factors Percent Error Deviations

2. Index Scientific Notation

3. Index

4. Measured Values Accuracy of a measurement is the closeness of the measurement to the true value. Precision refers to the reproducibility within a group of measurements.

5. Index Precision, Accuracy and Error Accuracy = % Error = 100 X (Experimental – Actual) Actual Value Precision = % Deviations = 100 X ( ave. deviation) mean deviation = l measured – mean l

6. Index Measuring values More Precise

7. Index Measured Values: Precision Significant Digits (means MEASURED) –ALL Numbers are important –need Rules to know how many to write

8. Index Sig Fig Rules 1. 4567 2. 34.989 3. 0.006040 4. 45.0387 5. 2.00 6. 34.900 7. 5000 8. 0.00783 9. 900. 10. 45078

9. Index Sig Fig Rules : multiply and divide Answer has same number of significant digits as the number with the least significant digits. Ex. 12.65 x 42.1 = 532.565 XX =533 4 3 3

10. Index RULES: ADD AND SUBTRACT decimal place determines the number of digits. The last COMMON decimal place is the last number you can justify Ex. 10.13 + 20.5 30.63 X = 30.6

11. Index

12. Dimensional What? Analysis

13. Index DIMENSIONAL ANALYSIS

14. UV radiation is very energetic and causes your skin to burn. If you are exposed to 1.00 Mole of photons with a wavelength of 305. nm, what amount of energy (in kilojoules per mole) are you being hit by? Speed of light = 2.998 x 10 8 m/s Plank’s Constant = 6.626 x 10 -34 J s

16. Index There’s more? Metrics

17. Index Types of Observations and Measurements We make QUALITATIVE observations of reactions — changes in color and physical state.We make QUALITATIVE observations of reactions — changes in color and physical state. We also make QUANTITATIVE MEASUREMENTS, which involve numbers.We also make QUANTITATIVE MEASUREMENTS, which involve numbers. Use SI units — based on the metric systemUse SI units — based on the metric system

18. Index UNITS OF MEASUREMENT Use SI units — based on the metric system LengthMassTimeTemperature Meter, m Kilogram, kg Seconds, s Celsius degrees, ˚C kelvins, K

19. Index Units of Length 1 kilometer (km) = ? meters (m)1 kilometer (km) = ? meters (m) 1 meter (m) = ? centimeters (cm)1 meter (m) = ? centimeters (cm) 1 centimeter (cm) = ? millimeter (mm)1 centimeter (cm) = ? millimeter (mm) 1 nanometer (nm) = 1.0 x 10 -9 meter1 nanometer (nm) = 1.0 x 10 -9 meter O—H distance = 9.4 x 10 -11 m 9.4 x 10 -9 cm 0.094 nm O—H distance = 9.4 x 10 -11 m 9.4 x 10 -9 cm 0.094 nm

20. Index