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Matter: Properties and Changes

Learn about the various properties of matter, including physical properties that can be observed without changing the substance's identity, such as color, density, and hardness. Discover how to calculate density and explore the concepts of physical changes, chemical properties, and chemical changes. Find out why a steel ship can float on water while a bar of steel sinks. Get insights into measuring density and understanding buoyancy.

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Matter: Properties and Changes

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  1. Matter: Propertiesand Changes

  2. Physical Properties can be observed without changing the identity of the substance. Ex… ~ color ~ conductivity ~ taste ~ viscosity ~ odor ~ elasticity ~ size ~ hardness ~ shape ~ magnetism ~ texture ~ boiling/ melting point and many more…

  3. But one of the most useful isDensity: the amount of matter present in a given volume. ~ or how heavy a substance is compared to how much space it takes up A is more dense than B (there is more matter and less space); B and C are of similar densities b/c the ratios of matter and space are about the same Ice is less dense than water; it floats on water

  4. Calculating Density Density = mass / volume D = m/v m = Dv v = m/D Units: m = g v = mL or cm3 D = g/ml or g/cm3

  5. Density Problems 1. A nail has a vol. of 0.880 cm3 and a mass of 6.920 grams. What is the densityof the nail? D = 7.86 g/cm3 D = m/v D = 6.920 g ÷ 0.880 cm3 2. Vegetable oil has a density of 0.916 g/ml. Calculate the mass of 500.0 ml of oil. m = D × v m = 0.916 g/ml × 500.0 ml m = 458 grams 3. The density of a piece of wood is 0.86 g/cm3. What is the volume of the wood if its mass is 75 grams? v = m/D v = 75 g ÷ 0.86 g/cm3 v = 87 cm3

  6. Measuring Density To measure the density of an object… 1. find the mass of the object using a balance 2. find the volume of the object: a) for regular solids – use a ruler, l x w x h b) for irregular solids - use the water displacement method (unless solid dissolves or floats) c) for liquids – use a graduated cylinder

  7. Buoyancy - Density and buoyancy are physical properties - Buoyancy is the force with which a more dense fluid pushes a less dense substance upward

  8. Which of the following statements explains why a steel ship will float on water but a bar of steel will sink. A boat floats because….

  9. Physical Changes are changes in appearance only… NOT in chemical make-up Includes… ~ changes in size ~ changes in shape ~ changes in phase ~ dissolving

  10. Examples of physical changes... ~ breaking a window ~ melting a piece of ice ~ tearing / cutting a piece of paper ~ dissolving sugar in hot tea ~ painting wood ~ shaping metal

  11. Chemical Properties properties that explain HOW a substance will react or behave. The substance must be changed into something new to observe the property. Ex: ~ flammability ~ reactivity to…  water  acids  bases ~ ability to lose electrons (be oxidized)

  12. Chemical Changes Are changes that result in a recombination of atoms – the formation of NEW substance(s)! ~ you can’t get the original substance back without a chemical reaction. Evidence that a chemical change has occurred: ~ formation of precipitate (solid) ~ gas / bubbles given off ~ light given off ~ color change (if new substance) ~ heat given off / absorbed (breaking/making chem. bonds)

  13. Examples of chemical changes: Striking a match releases heat and light and results in ash, smoke and gas Cooking bread changes the color, texture, odor, taste ~ baking bread ~ burning a match ~ silver tarnishing ~ a nail rusting ~ food rotting or souring

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