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Matter: Properties, Changes and Density

Matter: Properties, Changes and Density. Physical Properties. can be observed without changing the identity of the substance. Ex… ~ c o l o r ~ conductivity ~ taste ~ viscosity ~ odor ~ elasticity ~ size ~ hardness ~ shape ~ magnetism

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Matter: Properties, Changes and Density

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  1. Matter: Properties, Changes and Density

  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. DENSITY DEMO

  8. Density Measurements

  9. Put the following liquids in order of increasing density: water, salt water, alcohol, coke, diet coke • Alcohol • Diet Coke • Water • Coke • Salt water

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

  11. 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….

  12. Buoyancy Lab… 1 penny = 2.5g 1. Cut a 10 cm X 10 cm sheet of aluminum foil. Place the foil sheet in the water. Place pennies, one by one, on your aluminum sheet until it sinks. 2. Now take your 10 cm X 10 cm sheet of aluminum foil and shape it into a boat. Place your boat in the water. Place pennies, one by one, in your boat until it sinks. 3. Summary:Why did the boat hold more pennies? Explain using the words density, volume, and buoyancy.

  13. 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…

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

  15. 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

  16. 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)

  17. 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)

  18. 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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