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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.
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(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:
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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?
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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.
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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.
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(Questions 28-40) Classify the following as elements, compounds, heterogeneous or
homogeneous mixtures:
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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