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Name: ______________________________ Hr: _____ Date: _____________________ CHEMISTRY I CHAPTER 3, #2 1. Suggest a way to determine whether a colorless liquid is pure water or a solution of salt in the water, without tasting the liquid. ________________________________________________________________________ ________________________________________________________________________ (Questions 2-8) In the process of attempting to characterize a substance, a chemist makes the following observations, Label them as chemical or physical properties: _________________ _________________ _________________ _________________ _________________ _________________ 2. 3. 4. 5. 6. 7. The substance is a silvery white, lustrous metal. It melts at 649oC and boils at 1105 oC. Its density at 20 oC is 1.738 g/cm3. The substance burns in air, producing an intense white light. It reacts with chlorine to give a brittle white solid. The substance can be pounded into thin sheets or drawn into wires. _________________ 8. It is a good conductor of electricity. (Questions 9-24) Classify each of the following changes as physical or chemical: ____________ 9. the vaporization of solid carbon dioxide. ____________ 10. the explosion of solid TNT ____________ 11. the aging of an egg with a resultant unpleasant smell ____________ 12. the formation of a solid when honey is cooled ____________ 13. corrosion of aluminum metal. ____________ 14. melting of ice ____________ 15. pulverizing (crushing) an aspirin ____________ 16. digesting a candy bar ____________ 17. explosion of nitroglycerin ____________ 18. Hydrofluouric acid attack glass, and is used to etch calibration marks on glass laboratory utensils. ____________ 19. Marble statues deteriorate when attacked by acid rain. ____________ 20. Soap lathers when you wash your hands. ____________ 21. Grape juice ferments when yeast is added. ____________ 22. Hydrogen peroxide fizzes when applied to a wound ____________ 23. Isopropyl alcohol feels cool as it evaporates from the skin. ____________ 24. Acids produced by bacteria in plaque cause teeth to decay. Name: ______________________________ Hr: _____ Date: _____________________ 25. Describe the process of distillation. Does the separation of the components of a mixture by distillation represent a chemical or a physical change? ________________________________________________________________________ ________________________________________________________________________ 26. In a common laboratory experiment in general chemistry, students are asked to determine the relative amounts of benzoic acid and charcoal in a solid mixture. Benzoic acid is relatively soluble (will dissolve) in hot water, but charcoal is not. Devise a method for separating the two components of the mixture. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 27. Pure substance “X” is melted, and the liquid is placed in an electrolysis apparatus. When an electric current is passed through the liquid, a brown solid forms in one chamber and a white solid forms in the other chamber. Is substance “X” a compound or an element? EXPLAIN YOUR ANSWER. ________________________________________________________________________ ________________________________________________________________________ (Questions 28-40) Classify the following as elements, compounds, heterogeneous or homogeneous mixtures: _______________ _______________ _______________ _______________ _______________ _______________ _______________ _______________ _______________ _______________ _______________ _______________ _______________ 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. the mercury used in a thermometer air beach sand concrete aluminum foil sugar a solution of ethanol and water the atmosphere a carbonated soft drink (such as Sprite) iodine crystals seawater carbon dioxide gasoline