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Physical and Chemical Properties and Changes

Physical and Chemical Properties and Changes. GPS Standards: SC1. Students will analyze the nature of matter and its classifications. Identify substances based on chemical and physical properties .

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Physical and Chemical Properties and Changes

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  1. Physical and Chemical Properties and Changes • GPS Standards: SC1. Students will analyze the nature of matter and its classifications. • Identify substances based on chemical and physical properties. • SCSh5. Students will demonstrate the computation and estimation skills necessary for analyzing data and developing reasonable scientific explanations. • e. Solve scientific problems by substituting quantitative values, using dimensional analysis and/or simple algebraic formulas as appropriate. 8/10/10

  2. physical property = characteristic of a substance that can be observed or measured WITHOUT changing the identity (chemical formula) of the substance. Most physical properties do NOT depend on the size or source of the sample. • chemical property: characteristic of a substance that can be observed or measured only by performing a chemical reaction with the substance (the reaction causes a CHANGE in the substance’s formula). Most chemicalproperties do NOT depend on the size or source of the sample. • physical change = a change in the physical form or properties of a substance that occurs WITHOUT changing the identity (formula) of the substance. • chemical change = a CHANGE in the chemical formula of a substance that occurs through a chemical reaction, forming one or more new substances.

  3. density flammability fruit ripening batteries “dying” boiling color boiling point breathing burning precipitates forming neutralization shape reactivity shape/texture change sublimating volume condensing decomposition rate density flammability color reactivity boiling point decomposition rate shape volume boiling fruitripening shape/texture change batteries “dying” sublimating breathing condensing burning precipitates forming neutralization

  4. deposition changing mass/volume melting point phase color change acid/base character colored paper fading melting photosynthesis dissolving electrical conductivity evaporating hardness magnetic character mass density flammability magnetic character color reactivity boiling point decomposition rate mass shape acid/base character volume melting point phase electrical conductivity hardness boiling fruitripening shape/texture change batteries “dying” sublimating breathing condensing burning deposition precipitates forming changing mass/volume neutralization melting color change dissolving colored paper fading evaporating photosynthesis

  5. Properties can also be classified another way: extensive properties: depend on amount of matter that is present in the sample. Can be physical or chemical. examples = mass, volume, some chemical reactivities, etc. intensive properties: do NOT depend on amount of matter that is present in the sample. Can be physical or chemical. examples = melting/boiling points, density, hardness, electrical conductivity, magnetism, color, shape, reactivity, combustibility, acid/base character, etc.

  6. Density density (D) = the relationship between the mass (m) and volume (V) of a substance. acceptable units for mass include grams (g), kilograms (kg), etc. acceptable units for volume include cubic centimeters (cm3), liters (L), milliliters (mL), etc. acceptable units for density include g/cm3, g/L, g/mL, kg/L, etc. the volume measurement of a density problem can calculated in two ways: water displacement = method for measuring the volume of an irregular object. an object is dropped into a measured amount of water in a graduated cylinder or beaker. D = m V

  7. water displacement = method for measuring the volume of an irregular object. an object is dropped into a measured amount of water in a graduated cylinder or beaker. the difference between the initial volume of the water and the new volume of the water is equivalent to the object’s volume. measured size = method for measuring the volume of a regular object (such as a rectangular prism, sphere, or cylinder) by measuring the length of the sides/radius. practice problems: Ex1: If 15.68 g of a liquid occupy a space of 44.5 mL, what is the density of the liquid in g/cm3?

  8. Ex1: If 15.68 g of a liquid occupy a space of 44.5 mL, what is the density of the liquid in g/cm3? D = _____________ m = _____________ V = _____________ Ex2: The density of silver is 10.49 g/cm3.  If small bar of pure silver measures 3.4 cm by 1.8 cm by 3.7 cm, what would the mass be for this sample? D = _____________ m = _____________ V = _____________ ? 15.68 g 44.5 mL 1 mL = 1 cm3 ...so 44.5 mL = 44.5 cm3 D = m V = 15.68 g = 44.5 cm3 .35 g/cm3 V = lwh = (3.4 cm)(1.8 cm)(3.7 cm) 10.49 g/cm3 ? 22.644 cm3 V = 22.644 cm3 VV D = m V m = VD = (22.644 cm3)(10.49 g/cm3) = 237.54 g

  9. Ex3: The density of a lead cylinder is 11.34 g/cm3.  What would be the length of a 364.5 g cylinder of this metal if its radius is 2.7 cm? D = _____________ m = _____________ V = _____________ m = VD V = m D __ ___ D D 11.34 g/cm3 364.5 g ? V = 364.5 g = 11.34 g/cm3 32.14 cm3 V = r2h __ _____ r2r2 32.14 cm3= (2.7 cm)2 h = V = r2 1.40 cm

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