HN HW: Changes and Properties

1. Indications of a chemical change List five indications (observations) that a chemical change has taken place. 2. Physical Properties Classify each of the following physical properties as intensive (I) or extensive (E). Intensive Color (on the macroscopic scale) Density Boiling Point Specific Heat Extensive Mass Energy 3. Physical and Chemical Property Classify each of the following as a physical or chemical property. Physical Property iron is more dense than aluminum oil and water do not mix mercury melts at -39ºC Chemical Property iron and oxygen form rust magnesium burns brightly when ignited 4. Chemical Change What indication(s) tells you that each of these is a chemical change? a) food spoils odor color change forms precipitate b) an antacid tablet fizzes in water change in color odor production of gas c) a firecracker explodes change in temperature production of gas change in color 5. Physical and Chemical Changes What kind of change (physical or chemical) occurs when a compound is separated into its components? Explain your answer 6. Physical and Chemical Changes Classify each of the following as a physical or chemical change. Physical Change bending a piece of wire melting ice dissolving salt in water Chemical Change rusting nail burning coal 7. A friend tells you that, “Because composition (what it's made up of) does not change during a physical change, the appearance of a substance does not change.” Is your friend correct? Explain your answer. 8. Does the following diagram represent a physical or chemical change? Explain your choice. 9. Specific Heat Calculations Aluminum has a specific heat capacity of 0.90 J How much energy is required to heat a 10.0 g block of aluminum from 300°C to 330°C? Include units and correct significant digits. Q = 300 J 10. Water has a specific heat capacity of 4.18 J If a sample needs 15,675 J of energy to heat from 0.5°C to 75.0°C, determine the mass of the cold water sample. Include units and correct significant digits.m = 50.3 g 11. A rectangular block of lead (Pb) measures 2.00 cm x 3.00 cm x 4.50 cm. If the density of Pb is11.34 g calculate the mass of the block.Show your work in the table below -- assume each box is a fence. Put your answer in the top right box, and leave the bottom right empty. Don't forget units and significant digits! 27.0 cm3 11.34 g 306 g 1 cm3 12. Endothermic v. Exothermic Determine whether each of the following is a chemical or physical changeandif it's endothermic or exothermic. Chemical or Physical Change? Endothermic or Exothermic? Breaking an instant-use cold pack Chemical Change Endothermic Liquid water freezes Physical Change Exothermic