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Updated Mar 21, 2026
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5 Differences Between Exothermic and Endothermic Reactions with Examples
Reuben Cowell
@reubencowell
1 / 4
Endothermic Reactions and Reaction Profiles
Endothermic Reactions
Endothermic reactions absorb energy from the surroundings, often resulting in a temperature decrease. These reactions are less common than exothermic ones.
Definition: An endothermic reaction is a reaction that takes in energy from the surroundings.
Example: The reaction between citric acid and sodium hydrogencarbonate is an endothermic process.
Other examples of endothermic reactions include:
- Thermal decomposition
Highlight: Endothermic reactions have practical applications, such as in instant ice packs that cool without refrigeration.
Reaction Profiles
Reaction profiles visually represent the energy changes during chemical reactions. They show:
- Relative energies of reactants and products
- Energy changes throughout the reaction progress
- Whether a reaction is exothermic or endothermic
Vocabulary: Activation energy is the minimum amount of energy needed for reactants to collide and initiate a reaction.
Reaction profiles illustrate key differences between exothermic and endothermic reactions:
- Exothermic reactions: Energy of products is lower than reactants, resulting in a negative overall energy change
- Endothermic reactions: Energy of products is higher than reactants, leading to a positive overall energy change
Highlight: Reaction profiles provide a visual representation of energy changes in chemistry, helping to distinguish between exothermic and endothermic reactions.
Energy Changes and Bond Energies in Chemical Reactions
Energy Changes in Reactions
Chemical reactions involve breaking existing bonds and forming new ones, which contributes to the overall energy change:
- Bond breaking: An endothermic process requiring energy input
- Bond formation: An exothermic process releasing energy
Highlight: The balance between energy required for bond breaking and energy released during bond formation determines whether a reaction is overall exothermic or endothermic.
Bond Energies and Energy Calculations
Every chemical bond has an associated bond energy that varies depending on the compound. These known bond energies can be used to calculate the overall energy change for a reaction.
Definition: The overall energy change is the sum of the energies needed to break bonds in the reactants minus the energy released when new bonds are formed in the products.
To calculate the energy change for a reaction:
- Determine the energy required to break original bonds
- Calculate the energy released by forming new bonds
- Subtract the energy to break bonds from the energy to form new bonds
Highlight: Understanding bond energy calculations is crucial for predicting and analyzing energy changes in chemistry.
This approach allows for the quantitative analysis of energy changes in reactions, providing insights into the thermodynamics of chemical processes.
Energy Changes and Reaction Profiles
The detailed examination of reaction profiles and energy changes in chemistry reveals the relationship between reactants and products in terms of energy.
Definition: Reaction profiles show energy changes throughout a reaction's progress, with energy on the y-axis and reaction progress on the x-axis.
Highlight: In exothermic reactions, products have lower energy than reactants (negative energy change), while in endothermic reactions, products have higher energy than reactants (positive energy change).
Example: How to calculate energy change in chemistry involves understanding bond breaking (endothermic) and bond forming (exothermic) processes.
Energy Transfer in Exothermic and Endothermic Reactions
Chemical reactions involve energy changes as chemicals store varying amounts of energy. The energy transfer between reactants, products, and surroundings determines whether a reaction is exothermic or endothermic.
Exothermic Reactions
Exothermic reactions transfer energy to the surroundings, typically manifested as a temperature rise. Common examples include:
- Burning fuels
- Neutralization reactions
- Many oxidation reactions
Definition: An exothermic reaction is a reaction that transfers energy to the surroundings.
Example: Hand warmers and heating systems utilize exothermic reactions to generate heat.
Practical Measurement
To measure energy transfer and determine if a reaction is exothermic or endothermic:
- Measure the initial temperature of reagents
- Place them in an insulated environment
- Allow the reaction to occur
- Measure the final temperature
Highlight: This practical method helps identify whether a reaction is exothermic or endothermic based on temperature changes.
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Most popular content: Endothermic Process
Energy Changes in Reactions
Explore the principles of energy changes in chemical reactions, focusing on exothermic and endothermic processes, bond energy, and calorimetry techniques. This summary covers key concepts such as activation energy, collision theory, and the functioning of fuel cells and batteries. Ideal for GCSE Chemistry students preparing for AQA Higher Triple exams.
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This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
5 Differences Between Exothermic and Endothermic Reactions with Examples
Reuben Cowell
@reubencowell
Understanding chemical reactions and their energy changes is crucial for chemistry students. Exothermic and endothermic reactions form the foundation of energy transfer in chemical processes, with distinct characteristics and real-world applications.
• Energy transferin chemical reactions involves either releasing... Show more
Endothermic Reactions and Reaction Profiles
Endothermic Reactions
Endothermic reactions absorb energy from the surroundings, often resulting in a temperature decrease. These reactions are less common than exothermic ones.
Definition: An endothermic reaction is a reaction that takes in energy from the surroundings.
Example: The reaction between citric acid and sodium hydrogencarbonate is an endothermic process.
Other examples of endothermic reactions include:
- Thermal decomposition
Highlight: Endothermic reactions have practical applications, such as in instant ice packs that cool without refrigeration.
Reaction Profiles
Reaction profiles visually represent the energy changes during chemical reactions. They show:
- Relative energies of reactants and products
- Energy changes throughout the reaction progress
- Whether a reaction is exothermic or endothermic
Vocabulary: Activation energy is the minimum amount of energy needed for reactants to collide and initiate a reaction.
Reaction profiles illustrate key differences between exothermic and endothermic reactions:
- Exothermic reactions: Energy of products is lower than reactants, resulting in a negative overall energy change
- Endothermic reactions: Energy of products is higher than reactants, leading to a positive overall energy change
Highlight: Reaction profiles provide a visual representation of energy changes in chemistry, helping to distinguish between exothermic and endothermic reactions.
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Energy Changes and Bond Energies in Chemical Reactions
Energy Changes in Reactions
Chemical reactions involve breaking existing bonds and forming new ones, which contributes to the overall energy change:
- Bond breaking: An endothermic process requiring energy input
- Bond formation: An exothermic process releasing energy
Highlight: The balance between energy required for bond breaking and energy released during bond formation determines whether a reaction is overall exothermic or endothermic.
Bond Energies and Energy Calculations
Every chemical bond has an associated bond energy that varies depending on the compound. These known bond energies can be used to calculate the overall energy change for a reaction.
Definition: The overall energy change is the sum of the energies needed to break bonds in the reactants minus the energy released when new bonds are formed in the products.
To calculate the energy change for a reaction:
- Determine the energy required to break original bonds
- Calculate the energy released by forming new bonds
- Subtract the energy to break bonds from the energy to form new bonds
Highlight: Understanding bond energy calculations is crucial for predicting and analyzing energy changes in chemistry.
This approach allows for the quantitative analysis of energy changes in reactions, providing insights into the thermodynamics of chemical processes.
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Improve your grades
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Energy Changes and Reaction Profiles
The detailed examination of reaction profiles and energy changes in chemistry reveals the relationship between reactants and products in terms of energy.
Definition: Reaction profiles show energy changes throughout a reaction's progress, with energy on the y-axis and reaction progress on the x-axis.
Highlight: In exothermic reactions, products have lower energy than reactants (negative energy change), while in endothermic reactions, products have higher energy than reactants (positive energy change).
Example: How to calculate energy change in chemistry involves understanding bond breaking (endothermic) and bond forming (exothermic) processes.
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Energy Transfer in Exothermic and Endothermic Reactions
Chemical reactions involve energy changes as chemicals store varying amounts of energy. The energy transfer between reactants, products, and surroundings determines whether a reaction is exothermic or endothermic.
Exothermic Reactions
Exothermic reactions transfer energy to the surroundings, typically manifested as a temperature rise. Common examples include:
- Burning fuels
- Neutralization reactions
- Many oxidation reactions
Definition: An exothermic reaction is a reaction that transfers energy to the surroundings.
Example: Hand warmers and heating systems utilize exothermic reactions to generate heat.
Practical Measurement
To measure energy transfer and determine if a reaction is exothermic or endothermic:
- Measure the initial temperature of reagents
- Place them in an insulated environment
- Allow the reaction to occur
- Measure the final temperature
Highlight: This practical method helps identify whether a reaction is exothermic or endothermic based on temperature changes.
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Is Knowunity really free of charge?
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user