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Dec 14, 2025
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Knowunity Philippines
@knowunityphilippines
Ever wondered why some chemical reactions happen instantly while others... Show more
Understanding energy in chemical reactions is simpler than it sounds. Every reaction either releases energy (like burning methane in your cooker) or absorbs energy (like dissolving ammonium chloride in water).
Think of the system as your reaction happening in a test tube, whilst the surroundings are everything else around it. Energy flows between them as heat or work, but the total energy never disappears - it just moves about.
The first law of thermodynamics is basically nature's accounting system: ΔU = q + w, where energy change equals heat plus work. For most reactions you'll study, we focus on enthalpy changes (ΔH) because they happen at constant pressure.
Key insight: When ΔH is negative, reactions release heat (exothermic). When positive, they absorb heat (endothermic).
Enthalpy measures the heat content of reactions at constant pressure. It's calculated as ΔH = H(products) - H(reactants), telling you exactly how much energy is involved.
Calorimetry lets you measure these energy changes using the formula q = mcΔT. If you dissolve 5g of ammonium chloride in 100g water and temperature drops from 25°C to 20°C, you've absorbed 2090 J of heat from the water.
Hess's law is your mathematical lifesaver - it states that enthalpy changes are the same regardless of reaction pathway. This means you can add and subtract known reactions to find unknown enthalpy changes.
For example, finding ΔH for carbon monoxide formation becomes straightforward when you combine the combustion reactions of carbon and carbon monoxide. You'll reverse equations and add them algebraically to reach your target reaction.
Exam tip: Always check your signs when using Hess's law - reversed reactions have opposite enthalpy signs.
Entropy measures disorder in systems, and nature loves chaos. When ice melts in tropical Philippines, entropy increases because liquid water molecules move more randomly than ordered ice crystals.
Entropy increases when solids become liquids, liquids become gases, or when more gas molecules form in reactions. Calculate entropy changes using ΔS°(rxn) = ΣS°(products) - ΣS°(reactants), remembering that elements have non-zero entropy values.
The second law of thermodynamics states that universe entropy always increases in spontaneous processes. For propane combustion in LPG, the positive entropy change shows increased disorder favours the forward reaction.
Remember: Unlike enthalpy, elements in their standard states don't have zero entropy values.
Gibbs free energy combines enthalpy and entropy to predict if reactions occur spontaneously. The equation ΔG = ΔH - TΔS shows that both energy and disorder matter, with temperature determining which dominates.
When ΔG is negative, reactions happen spontaneously. When positive, they need energy input. At zero, you've reached equilibrium.
Four scenarios determine spontaneity: reactions with negative ΔH and positive ΔS are always spontaneous, whilst positive ΔH and negative ΔS never occur spontaneously. The other combinations depend on temperature.
Standard free energy of formation works like enthalpy of formation. For calcium carbonate formation (limestone in Palawan), ΔG°(rxn) = -130.4 kJ/mol indicates spontaneous reaction under standard conditions.
Real-world connection: Photosynthesis has positive ΔG° , explaining why plants need solar energy input.
Chemical kinetics studies reaction speeds - thermodynamics tells you if reactions are possible, kinetics tells you how fast they'll happen. Even favourable reactions might crawl along without proper conditions.
Reaction rates measure concentration changes over time. For iron rusting in humid Philippine climate, if oxygen decreases at 0.15 M/min, the overall rate is 0.050 M/min.
Four main factors affect reaction speeds: concentration (more molecules mean more collisions), temperature (higher energy creates faster, more energetic collisions), surface area (more contact between reactants), and catalysts (alternative pathways with lower energy barriers).
Cooking rice demonstrates all these factors: smaller grains cook faster (surface area), pressure cookers reduce time (temperature), and proper water ratios matter (concentration effects).
Quick check: Rate expressions use negative signs for disappearing reactants and positive signs for forming products.
Rate laws express the mathematical relationship between reaction speed and reactant concentrations. For reaction aA + bB → products, the rate law is: Rate = k^m^n.
The rate constant (k) is your proportionality factor, whilst m and n are reaction orders that must be determined experimentally. You can't predict them from balanced equations.
Overall reaction order equals the sum of individual orders . These values tell you how sensitive your reaction is to concentration changes.
Understanding these relationships helps you control reaction conditions in everything from pharmaceutical manufacturing to food processing. Higher orders mean dramatic rate changes with small concentration adjustments.
Exam strategy: Always remember that reaction orders come from experiments, not from balanced chemical equations.
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.
You can download the app in the Google Play Store and in the Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
App Store
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
Knowunity Philippines
@knowunityphilippines
Ever wondered why some chemical reactions happen instantly while others take forever? Thermochemistry and chemical kinetics explain the energy changes and reaction speeds that govern everything from cooking rice to industrial processes in the Philippines.
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Understanding energy in chemical reactions is simpler than it sounds. Every reaction either releases energy (like burning methane in your cooker) or absorbs energy (like dissolving ammonium chloride in water).
Think of the system as your reaction happening in a test tube, whilst the surroundings are everything else around it. Energy flows between them as heat or work, but the total energy never disappears - it just moves about.
The first law of thermodynamics is basically nature's accounting system: ΔU = q + w, where energy change equals heat plus work. For most reactions you'll study, we focus on enthalpy changes (ΔH) because they happen at constant pressure.
Key insight: When ΔH is negative, reactions release heat (exothermic). When positive, they absorb heat (endothermic).
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Enthalpy measures the heat content of reactions at constant pressure. It's calculated as ΔH = H(products) - H(reactants), telling you exactly how much energy is involved.
Calorimetry lets you measure these energy changes using the formula q = mcΔT. If you dissolve 5g of ammonium chloride in 100g water and temperature drops from 25°C to 20°C, you've absorbed 2090 J of heat from the water.
Hess's law is your mathematical lifesaver - it states that enthalpy changes are the same regardless of reaction pathway. This means you can add and subtract known reactions to find unknown enthalpy changes.
For example, finding ΔH for carbon monoxide formation becomes straightforward when you combine the combustion reactions of carbon and carbon monoxide. You'll reverse equations and add them algebraically to reach your target reaction.
Exam tip: Always check your signs when using Hess's law - reversed reactions have opposite enthalpy signs.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Entropy measures disorder in systems, and nature loves chaos. When ice melts in tropical Philippines, entropy increases because liquid water molecules move more randomly than ordered ice crystals.
Entropy increases when solids become liquids, liquids become gases, or when more gas molecules form in reactions. Calculate entropy changes using ΔS°(rxn) = ΣS°(products) - ΣS°(reactants), remembering that elements have non-zero entropy values.
The second law of thermodynamics states that universe entropy always increases in spontaneous processes. For propane combustion in LPG, the positive entropy change shows increased disorder favours the forward reaction.
Remember: Unlike enthalpy, elements in their standard states don't have zero entropy values.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Gibbs free energy combines enthalpy and entropy to predict if reactions occur spontaneously. The equation ΔG = ΔH - TΔS shows that both energy and disorder matter, with temperature determining which dominates.
When ΔG is negative, reactions happen spontaneously. When positive, they need energy input. At zero, you've reached equilibrium.
Four scenarios determine spontaneity: reactions with negative ΔH and positive ΔS are always spontaneous, whilst positive ΔH and negative ΔS never occur spontaneously. The other combinations depend on temperature.
Standard free energy of formation works like enthalpy of formation. For calcium carbonate formation (limestone in Palawan), ΔG°(rxn) = -130.4 kJ/mol indicates spontaneous reaction under standard conditions.
Real-world connection: Photosynthesis has positive ΔG° , explaining why plants need solar energy input.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Chemical kinetics studies reaction speeds - thermodynamics tells you if reactions are possible, kinetics tells you how fast they'll happen. Even favourable reactions might crawl along without proper conditions.
Reaction rates measure concentration changes over time. For iron rusting in humid Philippine climate, if oxygen decreases at 0.15 M/min, the overall rate is 0.050 M/min.
Four main factors affect reaction speeds: concentration (more molecules mean more collisions), temperature (higher energy creates faster, more energetic collisions), surface area (more contact between reactants), and catalysts (alternative pathways with lower energy barriers).
Cooking rice demonstrates all these factors: smaller grains cook faster (surface area), pressure cookers reduce time (temperature), and proper water ratios matter (concentration effects).
Quick check: Rate expressions use negative signs for disappearing reactants and positive signs for forming products.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Rate laws express the mathematical relationship between reaction speed and reactant concentrations. For reaction aA + bB → products, the rate law is: Rate = k^m^n.
The rate constant (k) is your proportionality factor, whilst m and n are reaction orders that must be determined experimentally. You can't predict them from balanced equations.
Overall reaction order equals the sum of individual orders . These values tell you how sensitive your reaction is to concentration changes.
Understanding these relationships helps you control reaction conditions in everything from pharmaceutical manufacturing to food processing. Higher orders mean dramatic rate changes with small concentration adjustments.
Exam strategy: Always remember that reaction orders come from experiments, not from balanced chemical equations.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
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.
You can download the app in the Google Play Store and in the Apple App Store.
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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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
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