Intro to Chemical Reactions Types of properties & Signs a chemical reaction occurred
Pg 1 Expectation 1: Physical property Characteristics of a material that are observed without changing the identity of the substance. Examples: color, density, conductivity, malleability, melting point, boiling point, & Solubility: whether a substance will dissolve in another substance.
Pg 1 Expectation 2: Chemical property Characteristics of a material that describe how the material acts in the presence of other types of material. Examples: flammable, reacts with acid, corrosive, non-reactive with plastic, non-reactive with glass.
Pg 2 Expectation 4: Chemical Reaction A change that results in the production of new materials with new properties. The materials after the change are different than the materials present before the change. These new materials have different chemical & physical properties.
Pg 2 Expectation 4: Signs of a Chemical reaction Formation of a gas in the absence of heating. Examples: copper metal plus nitric acid produced brown gas Alka-Selzer plus water produces bubbles Color change that is not the result of color blending. Examples Copper penny plus acid turned blue Colorless gas turned orange liquid dots blue Clear liquids in long skinny vials turned white
Pg 2 Expectation 4: Signs of a Chemical Reaction Formation of a precipitate (a solid that does not dissolve in the liquid). Examples Red liquid plus clear liquid made a yellow/orange solid Clear liquids in long skinny vials turned white Change in odor Examples: Whoosh bottle odor went from repulsive/astringent to sort of sweet. Digestion
Pg 2 Expectation 4: Signs of a Chemical Reaction Absorption or release of energy, such as light or heat, w/o outside influence. We cannot use this one alone to determine if a chemical reaction occurred. Examples Baking soda plus vinegar gets cooler Glow sticks release light
Physical change A change that results in a difference in the material, but does not change the type of material. The composition of the material is the same after the change as it was before. The material still has the same chemical and physical properties as before. Examples: tearing paper, crumpling paper, coloring on paper, breaking glass, dissolving salt in water, getting paper wet