Presentation on theme: "Physical & Chemical Properties Physical & Chemical Changes"— Presentation transcript:
1Physical & Chemical Properties Physical & Chemical Changes Chapter 3Physical & Chemical PropertiesPhysical & Chemical Changes
2Physical PropertiesCharacteristics of a substance that can be observed without changing the identity of the substance.Examples include: mass, weight, volume, density, color, shape, hardness, & texture
3Physical Changes when only the form of a substance changes example = change in phase like solid ice to liquid water
4Properties that describe how a substance changes into new substances Chemical PropertiesProperties that describe how a substance changes into new substancesExamples include: flammability, support for burning, and the ease with which it combines with other substances
5Chemical ChangesDuring a chemical change, substances are changed into different substances.In other words, the composition of the substance changes.
6Chemical changes create new substances that can not be undone. Physical changes do not change the chemical composition of the substanceChemical changes create new substances that can not be undone.
7Evidence of a Chemical Change Color changeOdor changeEnergy changeFormation of a gas or solidNot easily reversed
8Color ChangesAs in the case of autumn leaves, a change in color is a clue to indicate a chemical change.
9Color ChangesPerhaps you have found a half eaten apple that turns brown. The reason is that a chemical change has occurred when food spoils.
10Odor ChangesIt only takes one experience with a rotten egg to learn that they smell different that fresh eggs.When eggs & food spoil, they undergo a chemical change.
11Energy Absorbed or Released the release or gain of energy by an object indicates a chemical change
12Energy is absorbed during chemical changes involved in cooking, like baking a cake
13Energy Released Energy can also be released during a chemical change. Fireworks release energy in a form of light that you can see.
14Reaction of Sodium With Chlorine Na&ClReaction of Sodium With ChlorineYou can also see that energy is released when in this movie clip sodium & chlorine are combined with water.
15Production of a SolidA solid that separates out of solution during a chemical change is called a precipitate.
16Production of a GasThe formation of a gas is a clue to chemical changes.The bubbles of gas that you observed form when an antacid is dropped into water is an example.
17Physical = Easily reversed After ice melts into liquid water, you can refreeze it into solid ice if the temperature drops.Freezing & melting are physical changes
18Chemical- Not easily reversed The substances produced during chemical changes however cannot easily change back into the original substances like when you burn wood.
19Chemical ReactionsChemical Changes are also called Chemical Reactions.Chemical reactions involve combining different substances.The chemical reaction produces a new substance with new & different physical and chemical properties.
20Law of Conservation of Mass Matter is never destroyed or created in chemical reactions.The particles of one substance are rearranged to form a new substance.The same # of particles that exist before the reaction exist after the reaction.