Index Measured Values Conversion Factors Percent Error Deviations

Index Scientific Notation

Index

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.

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

Index Measuring values More Precise

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

Index Sig Fig Rules

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

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 X = 30.6

Index

Dimensional What? Analysis

Index DIMENSIONAL ANALYSIS

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 = x 10 8 m/s Plank’s Constant = x J s

Index There’s more? Metrics

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

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

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 meter1 nanometer (nm) = 1.0 x meter O—H distance = 9.4 x m 9.4 x cm nm O—H distance = 9.4 x m 9.4 x cm nm

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