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Understanding Thermochemistry: Energy Concepts and Reactions Explained

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Angela :)

12/1/2025

Chemistry

Thermochemistry

51

Dec 1, 2025

3 pages

Understanding Thermochemistry: Energy Concepts and Reactions Explained

user profile picture

Angela :)

@angelach

Thermochemistry explores how energy transfers during chemical reactions and physical... Show more

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THERMO-CHEMISTRY
energy- the measure of the ability to do work.
units of
Joke (5)=
= newton x meter
energy:
TYPES OF ENERGY :
mechanical pot

Understanding Energy in Chemistry

Energy is simply the ability to do work, and we measure it in joules (J). You encounter different types of energy every day: mechanical (like a ball rolling), chemical (in batteries), electromagnetic (light), nuclear (from atoms), and thermal (heat).

Kinetic energy is the energy of motion calculatedas1/2×mass×velocity2calculated as 1/2 × mass × velocity², while potential energy is stored energy that can be released later. Potential energy comes in three main forms: elastic (like a stretched rubber band), chemical (in food and fuels), and gravitational (a book on a shelf).

The Law of Conservation of Energy states that energy cannot be created or destroyed—it only changes form. This means in any system, the total energy flowing in equals the energy flowing out. When heat transfers, it always moves from high temperature (hot) objects to low temperature (cold) objects, never the reverse.

💡 The faster molecules move, the higher their temperature! When something heats up, the rate of heat transfer actually increases—that's why a very hot object cools down quickly at first, then more slowly.

THERMO-CHEMISTRY
energy- the measure of the ability to do work.
units of
Joke (5)=
= newton x meter
energy:
TYPES OF ENERGY :
mechanical pot

Thermal Energy Transfer

Temperature measures the average kinetic energy of molecules—the faster they move, the higher the temperature. When most liquids heat up, they expand because their molecules move around more vigorously, taking up more space.

Energy transfers between objects in three key ways:

  • Conduction: Energy transfers through direct contact, especially in solids (like a metal spoon in hot soup)
  • Convection: Energy moves through fluids (liquids and gases) as warmer portions rise and cooler portions sink
  • Radiation: Energy travels as electromagnetic waves without needing a medium (like heat from the sun)

Thermochemical reactions fall into two important categories. Exothermic reactions release heat, feel hot, lose potential energy, and have a negative ΔH (change in enthalpy). Endothermic reactions absorb heat, feel cold, gain potential energy, and have a positive ΔH.

💡 Thermal equilibrium happens when the energy flowing into something equals the energy flowing out—that's when temperatures stop changing.

THERMO-CHEMISTRY
energy- the measure of the ability to do work.
units of
Joke (5)=
= newton x meter
energy:
TYPES OF ENERGY :
mechanical pot

Calculating Energy Changes

A thermochemical equation shows both the chemical reaction and its energy change. It's a powerful tool that tells us exactly how much heat is gained or lost when a reaction occurs.

To calculate the enthalpy change (ΔH) of a reaction, you subtract the standard heat of formation of the reactants from the standard heat of formation of the products. The sign tells you the reaction type: positive ΔH means endothermic (absorbing heat), while negative ΔH means exothermic (releasing heat).

For measuring heat transfer in calorimetry experiments, use this formula: Q = mcΔT, where Q is heat energy, m is mass, c is specific heat capacity, and ΔT is the temperature change (final minus initial temperature).

💡 When solving heat transfer problems, always identify all your variables first before plugging numbers into the equation. This simple strategy will help you avoid mistakes!



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What is the Knowunity AI companion?

Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.

Where can I download the Knowunity app?

You can download the app in the Google Play Store and in the Apple App Store.

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. 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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. 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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user

 

Chemistry

51

Dec 1, 2025

3 pages

Understanding Thermochemistry: Energy Concepts and Reactions Explained

user profile picture

Angela :)

@angelach

Thermochemistry explores how energy transfers during chemical reactions and physical changes. It connects chemistry with the energy changes we can observe and measure, helping us understand why some reactions feel hot and others feel cold.

THERMO-CHEMISTRY
energy- the measure of the ability to do work.
units of
Joke (5)=
= newton x meter
energy:
TYPES OF ENERGY :
mechanical pot

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Understanding Energy in Chemistry

Energy is simply the ability to do work, and we measure it in joules (J). You encounter different types of energy every day: mechanical (like a ball rolling), chemical (in batteries), electromagnetic (light), nuclear (from atoms), and thermal (heat).

Kinetic energy is the energy of motion calculatedas1/2×mass×velocity2calculated as 1/2 × mass × velocity², while potential energy is stored energy that can be released later. Potential energy comes in three main forms: elastic (like a stretched rubber band), chemical (in food and fuels), and gravitational (a book on a shelf).

The Law of Conservation of Energy states that energy cannot be created or destroyed—it only changes form. This means in any system, the total energy flowing in equals the energy flowing out. When heat transfers, it always moves from high temperature (hot) objects to low temperature (cold) objects, never the reverse.

💡 The faster molecules move, the higher their temperature! When something heats up, the rate of heat transfer actually increases—that's why a very hot object cools down quickly at first, then more slowly.

THERMO-CHEMISTRY
energy- the measure of the ability to do work.
units of
Joke (5)=
= newton x meter
energy:
TYPES OF ENERGY :
mechanical pot

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Thermal Energy Transfer

Temperature measures the average kinetic energy of molecules—the faster they move, the higher the temperature. When most liquids heat up, they expand because their molecules move around more vigorously, taking up more space.

Energy transfers between objects in three key ways:

  • Conduction: Energy transfers through direct contact, especially in solids (like a metal spoon in hot soup)
  • Convection: Energy moves through fluids (liquids and gases) as warmer portions rise and cooler portions sink
  • Radiation: Energy travels as electromagnetic waves without needing a medium (like heat from the sun)

Thermochemical reactions fall into two important categories. Exothermic reactions release heat, feel hot, lose potential energy, and have a negative ΔH (change in enthalpy). Endothermic reactions absorb heat, feel cold, gain potential energy, and have a positive ΔH.

💡 Thermal equilibrium happens when the energy flowing into something equals the energy flowing out—that's when temperatures stop changing.

THERMO-CHEMISTRY
energy- the measure of the ability to do work.
units of
Joke (5)=
= newton x meter
energy:
TYPES OF ENERGY :
mechanical pot

Sign up to see the contentIt's free!

Access to all documents

Improve your grades

Join milions of students

By signing up you accept Terms of Service and Privacy Policy

Calculating Energy Changes

A thermochemical equation shows both the chemical reaction and its energy change. It's a powerful tool that tells us exactly how much heat is gained or lost when a reaction occurs.

To calculate the enthalpy change (ΔH) of a reaction, you subtract the standard heat of formation of the reactants from the standard heat of formation of the products. The sign tells you the reaction type: positive ΔH means endothermic (absorbing heat), while negative ΔH means exothermic (releasing heat).

For measuring heat transfer in calorimetry experiments, use this formula: Q = mcΔT, where Q is heat energy, m is mass, c is specific heat capacity, and ΔT is the temperature change (final minus initial temperature).

💡 When solving heat transfer problems, always identify all your variables first before plugging numbers into the equation. This simple strategy will help you avoid mistakes!

We thought you’d never ask...

What is the Knowunity AI companion?

Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.

Where can I download the Knowunity app?

You can download the app in the Google Play Store and in the Apple App Store.

Is Knowunity really free of charge?

That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.

Can't find what you're looking for? Explore other subjects.

Students love us — and so will you.

4.9/5

App Store

4.8/5

Google Play

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. 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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

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

I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️

Thomas R

iOS user

Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades

Brad T

Android user

Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍

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

I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend

Aubrey

iOS user

Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀

Marco B

iOS user

THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE THE SCHOOLGPT. 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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!

Paul T

iOS user