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Using the graphic below, identify the following example chemical reactions as endothermic (right-side) or exothermic (left-side) by selecting the best graph for each. For help look to see if energy is released to the surroundings or if energy must be taken in from the surroundings. (4 points) Left-side Graph Right-side Graph Any reaction that absorbs more energy from the surroundings to proceed. Combustion reaction in a car as octane gas burns in the presence of oxygen. Ice from the freezer's dispenser falls on your kitchen floor and melts into a little cold puddle of water. A system that "feels hot or warm" to the touch. Skip to navigation

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To classify the given chemical reactions as either endothermic or exothermic, we can use the following characteristics:

  1. Endothermic Reactions: These reactions absorb energy from the surroundings. This means that energy must be taken in for the reaction to proceed, leading to a decrease in temperature of the surroundings.

  2. Exothermic Reactions: These reactions release energy to the surroundings. The result is that the surroundings become warmer, and the energy released can often be felt as heat.

Now, let's categorize the examples you provided:

  1. Any reaction that absorbs more energy from the surroundings to proceed - This is an endothermic reaction.

    • Graph: Right-side Graph (endothermic)

  2. Combustion reaction in a car as octane gas burns in the presence of oxygen - This reaction releases energy, typically in the form of heat and light.

    • Graph: Left-side Graph (exothermic)

  3. Ice from the freezer's dispenser falls on your kitchen floor and melts into a little cold puddle of water - Melting ice requires energy absorption from the surroundings, which is indicative of an endothermic process.

    • Graph: Right-side Graph (endothermic)

  4. A system that "feels hot or warm" to the touch - If a system feels warm to the touch, it is likely releasing energy, which indicates an exothermic reaction.

    • Graph: Left-side Graph (exothermic)

Summary:

  • Endothermic: Right-side Graph

    • Any reaction that absorbs more energy from the surroundings.
    • Ice melts into water.

  • Exothermic: Left-side Graph

    • Combustion reaction in a car.
    • A system that feels hot or warm to the touch.