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Physical Properties Physical Changes Chemical Properties Chemical Changes Physical Properties • Can be observed without changing the identity of the matter. Physical Properties What are some physical properties? • color • melting and boiling point • odor Physical Changes • Alters the form or appearance of a material but does not convert the material into new substance. Physical Changes – can be observed without changing the identity of the substance Some physical changes would be • boiling of a liquid • melting of a solid • dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION. Chemical Properties • Is a property of matter that describes a substance based on its ability to change into a new substance. • This property becomes apparent during a chemical reaction, and can only be observed by changing a substance's chemical identity. Examples of Chemical Properties • Reactivity • Flammability (the ability to catch on fire) • Toxicity (the ability to be poisonous), • Oxidation (the ability to react with oxygen, which causes apple slices to turn brown and iron to rust), • Sensitivity to light Chemical Changes • A change in matter that forms one or more new substances with different properties. Oxygen is highly reactive and can combine with almost any element. Hydrogen Hydrogen is highly flammabl Oxygen Hydrogen and Oxygen are both gasses. The reactants H2 and 02 H H O H H O Combine to form H2O H H H H The ProductsEnergy O O Water has completely different properties than the reactants that make it up. Hydrogen Oxygen Water Physical property or chemical Property? • When considering properties to help decide ask yourself “does observing the property cause a new substance to form?”. Signs of a Chemical Change • Heat (Exothermic) • Cooling (Endothermic) • Bubbles • Light • Precipitation • Color change Physical vs. Chemical • Examples: – melting point physical – flammable chemical – density physical – magnetic physical – tarnishes in air chemical Chemical or Physical Change