Ever wonder why some chemical reactions happen on their own... Show more
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K
Kael
12/10/2025
GenChem
CHEMISTRY REVIEWER
145
•
Dec 10, 2025
•
Comprehensive Chemistry Notes and Study Guide
K
Kael
@kaeliyyih
1 / 4
Thermodynamics and Thermochemistry
Think of thermodynamics as the rulebook for energy in chemistry - it tells us how heat, work, and energy move around during reactions. Thermochemistry specifically focuses on the heat changes that happen when chemicals react or change phases.
Endothermic reactions are like energy sponges - they absorb heat from their surroundings (like when ice melts and makes your drink cold). Exothermic reactions do the opposite, releasing heat energy (like when you burn gasoline in a car engine). You can tell which is which by looking at enthalpy (ΔH): negative ΔH means exothermic (heat released), positive ΔH means endothermic (heat absorbed).
Calorimetry is how we actually measure these heat changes using devices called calorimeters. The First Law of Thermodynamics is pretty straightforward - energy can't just appear or disappear, it only changes from one form to another.
Quick Tip: In thermochemical equations, the ΔH value tells you exactly how much energy is involved. For example, burning 1 mole of methane releases 890 kJ of energy .
Advanced Thermodynamics and Spontaneity
Here's where chemistry gets really interesting - entropy (S) measures how messy or disorganized a system is, and nature loves chaos! Gases are more disorganized than liquids, which are more disorganized than solids. Higher temperatures also mean more entropy because particles have more energy to move around randomly.
The Second Law of Thermodynamics says that spontaneous processes always increase the overall disorder of the universe. But here's the catch - just because a reaction releases heat doesn't mean it will happen spontaneously.
Gibbs Free Energy (ΔG) is the ultimate decision-maker using the formula ΔG = ΔH - TΔS. When ΔG is negative, the reaction happens on its own (spontaneous). When ΔG is positive, you need to force it. When ΔG equals zero, everything's in perfect balance (equilibrium).
Memory Hack: Think of ΔG as nature's "thumbs up or down" - negative means go, positive means stop!
Chemical Equilibrium Fundamentals
Chemical equilibrium happens when the forward and reverse reactions occur at exactly the same rate - it's like a perfectly balanced seesaw that never tips. The concentrations stop changing, but the reactions keep happening behind the scenes.
The equilibrium constant (K) tells you which side wins. When K > 1, you get more products than reactants. When K < 1, reactants dominate. This follows the Law of Mass Action, which gives us the mathematical relationship between product and reactant concentrations.
Le Chatelier's Principle is your go-to rule for predicting what happens when you mess with an equilibrium system. Add more reactants? The system shifts to make more products. Increase temperature on an endothermic reaction? More products form. Increase pressure? The system shifts toward whichever side has fewer gas molecules.
Real-World Connection: Your blood uses equilibrium principles to carry oxygen efficiently - hemoglobin picks up oxygen in your lungs and releases it in your tissues!
Equilibrium Applications and Key Concepts
Catalysts are like reaction cheerleaders - they speed up both forward and reverse reactions equally, so they don't change where the equilibrium sits, just how fast you get there. This makes them super useful in industrial processes where time equals money.
Chemical equilibrium principles power major industrial processes like the Haber process for making ammonia (essential for fertilizers). In biological systems, equilibrium controls everything from how oxygen binds to hemoglobin to how your body maintains proper pH levels.
Environmental processes also rely heavily on equilibrium - carbon dioxide dissolving in ocean water is a massive equilibrium system that affects global climate patterns. Understanding these principles helps scientists predict and control how chemical systems behave under different conditions.
Future Applications: Mastering equilibrium concepts prepares you for advanced chemistry, environmental science, and even biochemistry careers where these principles are essential tools.
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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
Comprehensive Chemistry Notes and Study Guide
K
Kael
@kaeliyyih
Ever wonder why some chemical reactions happen on their own while others need a push? Thermodynamics and chemical equilibrium are the keys to understanding how energy flows in chemical reactions and why reactions sometimes seem to "balance out" instead of... Show more
Thermodynamics and Thermochemistry
Think of thermodynamics as the rulebook for energy in chemistry - it tells us how heat, work, and energy move around during reactions. Thermochemistry specifically focuses on the heat changes that happen when chemicals react or change phases.
Endothermic reactions are like energy sponges - they absorb heat from their surroundings (like when ice melts and makes your drink cold). Exothermic reactions do the opposite, releasing heat energy (like when you burn gasoline in a car engine). You can tell which is which by looking at enthalpy (ΔH): negative ΔH means exothermic (heat released), positive ΔH means endothermic (heat absorbed).
Calorimetry is how we actually measure these heat changes using devices called calorimeters. The First Law of Thermodynamics is pretty straightforward - energy can't just appear or disappear, it only changes from one form to another.
Quick Tip: In thermochemical equations, the ΔH value tells you exactly how much energy is involved. For example, burning 1 mole of methane releases 890 kJ of energy .
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Advanced Thermodynamics and Spontaneity
Here's where chemistry gets really interesting - entropy (S) measures how messy or disorganized a system is, and nature loves chaos! Gases are more disorganized than liquids, which are more disorganized than solids. Higher temperatures also mean more entropy because particles have more energy to move around randomly.
The Second Law of Thermodynamics says that spontaneous processes always increase the overall disorder of the universe. But here's the catch - just because a reaction releases heat doesn't mean it will happen spontaneously.
Gibbs Free Energy (ΔG) is the ultimate decision-maker using the formula ΔG = ΔH - TΔS. When ΔG is negative, the reaction happens on its own (spontaneous). When ΔG is positive, you need to force it. When ΔG equals zero, everything's in perfect balance (equilibrium).
Memory Hack: Think of ΔG as nature's "thumbs up or down" - negative means go, positive means stop!
Sign up to see the contentIt's free!
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Improve your grades
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Chemical Equilibrium Fundamentals
Chemical equilibrium happens when the forward and reverse reactions occur at exactly the same rate - it's like a perfectly balanced seesaw that never tips. The concentrations stop changing, but the reactions keep happening behind the scenes.
The equilibrium constant (K) tells you which side wins. When K > 1, you get more products than reactants. When K < 1, reactants dominate. This follows the Law of Mass Action, which gives us the mathematical relationship between product and reactant concentrations.
Le Chatelier's Principle is your go-to rule for predicting what happens when you mess with an equilibrium system. Add more reactants? The system shifts to make more products. Increase temperature on an endothermic reaction? More products form. Increase pressure? The system shifts toward whichever side has fewer gas molecules.
Real-World Connection: Your blood uses equilibrium principles to carry oxygen efficiently - hemoglobin picks up oxygen in your lungs and releases it in your tissues!
Sign up to see the contentIt's free!
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Equilibrium Applications and Key Concepts
Catalysts are like reaction cheerleaders - they speed up both forward and reverse reactions equally, so they don't change where the equilibrium sits, just how fast you get there. This makes them super useful in industrial processes where time equals money.
Chemical equilibrium principles power major industrial processes like the Haber process for making ammonia (essential for fertilizers). In biological systems, equilibrium controls everything from how oxygen binds to hemoglobin to how your body maintains proper pH levels.
Environmental processes also rely heavily on equilibrium - carbon dioxide dissolving in ocean water is a massive equilibrium system that affects global climate patterns. Understanding these principles helps scientists predict and control how chemical systems behave under different conditions.
Future Applications: Mastering equilibrium concepts prepares you for advanced chemistry, environmental science, and even biochemistry careers where these principles are essential tools.
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.
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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