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Questions and Answers
What does a reaction profile diagram represent?
What does a reaction profile diagram represent?
Activation energy is not necessary for a chemical reaction to occur.
Activation energy is not necessary for a chemical reaction to occur.
False
What is the role of a catalyst in a chemical reaction?
What is the role of a catalyst in a chemical reaction?
A catalyst speeds up the rate of a chemical reaction without being used up.
A substance that reduces the activation energy and speeds up a reaction is called a ___________.
A substance that reduces the activation energy and speeds up a reaction is called a ___________.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What type of reaction absorbs heat from its surroundings?
What type of reaction absorbs heat from its surroundings?
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Exothermic reactions feel cold to the touch.
Exothermic reactions feel cold to the touch.
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What is formed during an exothermic reaction?
What is formed during an exothermic reaction?
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In an endothermic reaction, the energy needed to break existing bonds is __________ than the energy released when new bonds are formed.
In an endothermic reaction, the energy needed to break existing bonds is __________ than the energy released when new bonds are formed.
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Which of the following is an example of an exothermic reaction?
Which of the following is an example of an exothermic reaction?
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Photosynthesis is an endothermic reaction.
Photosynthesis is an endothermic reaction.
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What happens to temperature during an exothermic reaction?
What happens to temperature during an exothermic reaction?
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Match the following reactions with their types:
Match the following reactions with their types:
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Study Notes
Endothermic and Exothermic Reactions
- Chemical reactions involve energy release or absorption. Energy can take forms like heat, light, or electricity.
- Energy in reactions comes from breaking existing bonds (requiring energy input) and forming new bonds (releasing energy).
- Reactions can be classified as endothermic or exothermic based on energy transfer.
Endothermic Reactions
- Require energy input (heat) to proceed.
- Absorb heat from surroundings.
- Feel cold to the touch, because heat is being absorbed in the process.
- Example: liquid ice packs (reaction with water and ammonium nitrate), photosynthesis.
Exothermic Reactions
- Release energy (heat) during the process.
- Give off heat.
- Feel warm or hot to the touch, because heat is being released.
- Example: burning of wood, explosion of dynamite, rusting
Overall Energy Changes in Reactions
- In endothermic reactions, the energy needed to break existing bonds is greater than the energy released when new bonds are formed.
- In exothermic reactions, the energy released when forming new bonds is greater than the energy taken in to break existing bonds.
Reaction Profile Diagrams
- Show the energy changes during a chemical reaction.
- The difference between reactants and products, on a reaction profile graph, is the energy change in the reaction.
- The diagram shows the progress of the reaction.
Activation Energy
- The minimum amount of energy required to start a chemical reaction.
- Without this energy, a reaction won't happen.
- Examples:
- Striking a match requires enough energy to start combustion.
- Gasoline requires a spark (enough energy input) to burn in air.
Catalysts
- Substances that speed up chemical reactions without being used up in the process.
- Catalysts reduce the activation energy (the required minimum energy to start the reaction), so less energy is needed to get the reaction going.
- Examples: Enzymes are biological catalysts.
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Description
Test your understanding of endothermic and exothermic reactions with this quiz. Explore key concepts such as energy absorption and release, and learn about examples of each type of reaction. Perfect for students studying chemistry.
