chapter1hwq - CHAPTER 1 KEYS TO THE STUDY OF CHEMISTRY Most...

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1-1 CHAPTER 1 KEYS TO THE STUDY OF CHEMISTRY Most numerical problems will have two answers, a “calculator” answer and a “true” answer. The calculator answer, as seen on a calculator, will have one or more additional significant figures. These extra digits are retained in all subsequent calculations to avoid intermediate rounding error. Rounding of a calculator answer to the correct number of significant figures gives the true (final) answer. 1.1 a) A shows a physical change. The substance changes from a solid to a gas. b) B shows a chemical change. Two diatomic elements form from a diatomic compound. c) Both A and B result in different physical properties. Physical and chemical changes result in different physical properties. d) B is a chemical change; therefore, it results in different chemical properties. e) A does result in a change in state. The substance changes from a solid to a gas. 1.2 Plan: Apply the definitions of the states of matter to a container. Next, apply these definitions to the examples. Solution: Gas molecules fill the entire container; the volume of a gas is the volume of the container. Solids and liquids have a definite volume. The volume of the container does not affect the volume of a solid or liquid. a) The helium fills the volume of the entire balloon. The addition or removal of helium will change the volume of a balloon. Helium is a gas . b) At room temperature, the mercury does no completely fill the thermometer. The surface of the liquid mercury indicates the temperature. c) The soup completely fills the bottom of the bowl, and it has a definite surface. The soup is a liquid , though it is possible that solid particles of food will be present. 1.7 a) and c) can be reversed with temperature; the dew can evaporate and the ice cream refrozen. The other two, b) and d), involve chemical changes and cannot be reversed.
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chapter1hwq - CHAPTER 1 KEYS TO THE STUDY OF CHEMISTRY Most...

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