Properties of Matter Prof. Bixler

4.1 Properties of Substances Properties are characteristics of a substance that give it a unique identity Physical Properties are the inherit characteristics of a substance that can be determined without altering its composition like physical state, density, melting and boiling points, color, taste and odor

Name the Physical Properties

Chemical Properties Chemical Properties = describe the ability of a substance to form new substances either by reaction with other substances or by decomposition Reactivity or lack thereof of a substance with another is a chemical property No two substances have exactly the same physical and chemical properties

Change Physical Change: effect changes of physical properties only Ex. Cutting, bending, melting, boiling, separating, density measurement Chemical Change: occurs when new substances are formed that have different properties and composition than the original substance Ex. Burning, reacting, baking, exploding

Chemical or Physical Change?

Chemical Reactions (RXN) Chemical change is expressed in the form of chemical equations Chemical change = chemical reaction (rxn) Reactants= what you begin with (left of the arrow in a chemical equation) Products = what you end with (right of the chemical equation)

Laws of Conservation of Matter and Energy Law of Conservation of Matter states that no change is observed in the total mass of the substances involved in a a chemical change OR the mass of reactants = mass of products Law of Conservation of Energy states that energy can neither be created nor destroyed though it can be can be changed to another form

Energy Energy is the capacity to do work There are two major forms Potential energy: stored energy or energy something possesses due to its position Kinetic energy: energy in motion Heat: is measured in Joules in the metric system, but calorie is the unit you are most familiar with 1 calorie = 4.18 Joules 1,000 calorie = 1 nutritional Calorie = 1 kcal

Energy in Reactions Heat given off is called exothermic and could be written in a chemical equation as a product Heat may be absorbed in a reaction and would be written as a reactant.

Is it endothermic or exothermic?