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 Problem Solving Center eMedia Exercises

1.81 Experiment with the Phases of the Elements activity (eChapter 1.2). (a) How many elements are liquids at room temperature and what are they? (b) Choose two temperatures—one higher and one lower than room temperature—and determine how many elements are liquids at those temperatures.

1.82 Watch the Electrolysis of Water movie (eChapter 1.2). (a) How can you tell from this experiment that water is a compound and not an element? (b) If you were to perform a similar experiment using liquid bromine instead of liquid water in the apparatus, what would you expect to happen?

1.83 The principle that oppositely charged particles attract one another and like charges repel one another is summarized in Coulomb's law. Try some experiments using the Coulomb's Law activity (eChapter 1.3) to get a feel for the magnitudes of attractive and repulsive forces between charged particles. (a) Between which particles is the attractive force the stronger: a particle with a charge of at a distance of 3 Å from a particle with a charge of or a particle with a charge of at a distance of 2 Å from a particle with a charge of (b) Consider a particle with a charge of at a distance of 5 Å from a particle with a charge of If there were another negatively charged particle in between the two, what would you expect to happen to the magnitude of the attractive force between them?

1.84 The Changes of State movie (eChapter 1.3) shows what happens to a solid when it is heated. (a) Describe the changes that occur. (b) Is the change from solid to liquid a chemical change or a physical change? (c) Is the change from liquid to gas a chemical change or a physical change? (d) Is enough information given to determine whether the original solid is an element, a compound, or a mixture? Explain.

1.85 (a) Use the Significant Figures activity (eChapter 1.5) to verify your answers to Exercises 1.39 and 1.40. (b) Is it possible for the sum of a column of numbers, each containing two significant figures, to have more than two significant figures? Explain. (c) How many significant figures should there be in the answer to the following calculation?

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