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Questions and Answers
Which type of reaction is associated with the absorption of heat?
What is the nature of heat release in exothermic reactions?
What do the prefixes 'endo' and 'exo' signify in the context of endothermic and exothermic reactions?
In a campfire, which type of reaction occurs that makes the surroundings warm?
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Why does a glass of lemonade become colder when ice cubes in it begin to melt?
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What is the fundamental thermodynamic quantity that measures the heat content of a system?
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Which unit is enthalpy generally expressed in?
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What type of reaction involves the breaking of old bonds and the formation of new bonds?
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Which type of reaction releases heat energy during the reaction?
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What distinguishes endothermic reactions from exothermic reactions?
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Study Notes
Endothermic and Exothermic Reactions
- Reactions can be categorized into two types based on the aspect of heat involved: endothermic reactions and exothermic reactions.
Definition of Endothermic and Exothermic Reactions
- Endothermic reactions are associated with the absorption of heat.
- Exothermic reactions are associated with the release of heat.
- The prefixes "endo" and "exo" signify inside and outside, respectively, and "thermic" is related to thermal energy (or heat).
The Endothermic and Exothermic Process
- Enthalpy (H) is a fundamental thermodynamic quantity that measures the heat content of a system.
- Enthalpy is expressed in Joules (J) or kilo-Joules (kJ).
- The enthalpy of a particular system depends on the internal energy of the system and the work done on or by the system.
- In the context of chemical reactions, we consider the enthalpy of reaction (ΔH).
Enthalpy for Endothermic and Exothermic Reactions
- ΔH can be positive or negative depending on the enthalpy of the reactants and that of the products.
- Endothermic reactions: ΔH > 0, heat is absorbed during the reaction.
- Exothermic reactions: ΔH < 0, heat is released during the reaction.
Endothermic vs Exothermic
- Endothermic reactions:
- Associated with absorption of heat energy.
- Enthalpy of reactants > enthalpy of products.
- ΔH > 0.
- Exothermic reactions:
- Associated with release of heat energy.
- Enthalpy of products > enthalpy of reactants.
- ΔH < 0.
Examples of Endothermic and Exothermic Reactions
- Melting of ice: endothermic process, absorbs heat from the surroundings.
- Photosynthesis: endothermic reaction, absorbs energy from sunlight.
- Combustion reactions: exothermic reactions, release heat energy and/or light energy.
- Nuclear fission: exothermic reaction, releases a high amount of energy.
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Description
Test your knowledge on endothermic and exothermic reactions with questions related to heat production, heat absorption, and state changes. Explore the fundamental concepts of these reactions in everyday scenarios.
