Questions and Answers
What is exothermic reactions?
Chemical reactions that give out heat
What is endothermic reaction?
Chemical reactions that take in heat
Why is breaking of bonds in the reactants in a chemical reaction an endothermic process?
It requires energy
Why is making of bonds to form the products of a chemical reaction an exothermic process?
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The reaction is exothermic if the energy released in making the products is greater than the energy needed to break the bonds in the reactants.
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Why is combustion of methane an exothermic reaction?
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What is the name of the input energy that starts off the reaction in all reactions?
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Is combustion an endothermic reaction?
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What is heat of combustion?
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Why is polystyrene cup used as a simple calorimeter?
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Study Notes
Exothermic Reactions
- Exothermic reactions release heat into the environment.
- Energy released during product formation exceeds the energy required to break reactant bonds.
- Example: Combustion of methane, which gives off substantial heat.
Endothermic Reactions
- Endothermic reactions absorb heat from their surroundings.
- Energy is required to break bonds in the reactants, making it an input-driven process.
Bond Energy and Reactions
- Breaking bonds in reactants necessitates energy input; hence, it is characterized as endothermic.
- Forming bonds in products results in energy release, categorizing that process as exothermic.
Activation Energy
- Activation energy is the energy needed to initiate a chemical reaction.
- It serves as the energy threshold that reactants must overcome to form products.
Characteristics of Combustion
- All combustion reactions are classified as exothermic due to the heat generated.
- Heat of combustion refers to the energy change associated with the burning of a substance.
Calorimetry
- Polystyrene cups are utilized as simple calorimeters because they are effective thermal insulators, minimizing heat exchange with the environment.
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Test your knowledge about exothermic and endothermic reactions with these flashcards. Learn the definitions and key concepts associated with heat exchange in chemical processes. Perfect for students studying chemistry and understanding thermodynamics.
