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physical and chemical Properties

physical and chemical Properties. Sections 2.2 and 2.3. What is a Physical Property?. Any characteristic of a material that can be observed or measured without changing the composition of the substances in the material.

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physical and chemical Properties

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  1. physical and chemical Properties Sections 2.2 and 2.3

  2. What is a Physical Property? • Any characteristic of a material that can be observed or measured without changing the composition of the substances in the material. • Viscosity, conductivity, malleability, harness, melting and boiling points, density, and temperature are just a few examples.

  3. Viscosity • The tendency of a liquid to keep from flowing- its resistance to flowing. • The higher the viscosity of a liquid, the slower the liquid moves. • When a substance is heated, the viscosity of that substance lowers.

  4. Conductivity • A material’s ability to allow heat to flow. • Materials with a high conductivity are called conductors.

  5. Malleability • The ability of a solid (metal) to be shaped without breaking.

  6. Hardness, Melting & Boiling Points • To test hardness of material, you see which material can scratch the other. • Melting Point: The temperature at which a substance changes from a solid to liquid. • Boiling Point: The temperature at which a substance boils.

  7. Density • Density is a ratio of the mass of a substance to its volume d=m/v • Objects made out of the same material have the same density. • Density can be used to test the purity of a substance.

  8. Using Properties to Separate Mixtures • Filtration: A process that separates materials based on the size of their particles by using a strainer or filter. • Distillation: A process that separates the substance in a solution based on their boiling points.

  9. Physical Changes • Occurs When some of the properties of a material change, but the substances in the material remain the same. • Some physical changes can be reversed. • Freezing, melting, then freezing water again

  10. What is a Chemical Property? • Any ability to produce a change in the composition of matter. • Can only be observed when the substances in a sample of matter are changing into different substances.

  11. Examples Flammability Reactivity • Flammability • The material’s ability to burn in the presence of oxygen. • Lighting a candle • Reactivity • How readily a substance combines chemically with another substance. • Oxygen reacts easily with most elements. When oxygen reacts with iron and water rust forms.

  12. Recognizing a Chemical Change • A chemical change occurs when a substance reacts and forms one or more new substances. • Three common types of evidence: • Change of Color • Production of Gas • Formation of a Precipitate • Any solid that forms and separates from a liquid mixture.

  13. Is it Chemical or Physical? • Don’t be fooled! • A color change or production of gas doesn’t always mean that a chemical change has taken place. • Ask yourself this: • Are different substances present after the change takes place? • If you answer “no” then it’s a physical change • If you answer “yes then it’s a chemical change

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