1. UNIT 3
REVIEW MATERIAL

3. Properties
Physical vs. Chemical

4. What is a property?
A property is an identifying characteristic of a substance.
There are two groups of properties that are important to forensic scientists when identifying substances:
Physical properties
Chemical properties

5. Chemical Properties
A chemical property describes the behavior of a substance when it reacts or combines with another substance.
Examples of chemical properties:
Wood combining with oxygen in the air to burn or combust
Suspect specimen of heroin mixed with Marquis reagentColor change to purple indicates positive result for heroin

6. Physical Properties
A physical property describes a substance without reference to any other substance.
Physical properties can be measured without altering a substance’s chemical composition.
Physical properties are only associated with the physical existence of the substance
Examples of physical properties:
Weight, Volume, Color, Boiling Points, and Melting Points

7. Measuring Physical Properties
Temperature
Weight
Mass
Density

8. Using the metric and English system of measurements
Calculations
Using the metric and English system of measurements

9. Measurement System
Scientists throughout the world use the metric system of measurement.
The metric system has basic units of measurement for length, mass, and volume; they are the meter, gram, and liter, respectively.
The following are common prefixes used in the metric system: deci, centi, milli, micro, nano, kilo, and mega.