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9: Energy and Chemical Reactions

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    • 9.1: Energy
      When we speak of using energy, we are really referring to transferring energy from one place to another. Although energy is used in many kinds of different situations, all of these uses rely on energy being transferred in one of two ways. Energy can be transferred as heat or as work.
    • 9.2: Temperature - Random Motion of Molecules and Atoms
      Three different scales are commonly used to measure temperature: Fahrenheit (expressed as °F), Celsius (°C), and Kelvin (K).
    • 9.3: Temperature Changes - Heat Capacity
      The specific heat of a substance is the amount of energy required to raise the temperature of 1 gram of the substance by 1 degree Celsius.
    • 9.4: Energy and Heat Capacity Calculations
      Heat is a familiar manifestation of transferring energy. When we touch a hot object, energy flows from the hot object into our fingers, and we perceive that incoming energy as the object being “hot.” Conversely, when we hold an ice cube in our palms, energy flows from our hand into the ice cube, and we perceive that loss of energy as “cold.” In both cases, the temperature of the object is different from the temperature of our hand.
    • 9.5: Endothermic and Exothermic Reactions
      Chemical processes are labeled as exothermic or endothermic based on whether they give off or absorb energy, respectively.

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