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AP Chemistry
Dec 12, 2025
70
4 pages
Dive into the world of reaction kinetics, where we explore how quickly chemical reactions happen and what affects... Show more
![[propene] /mol dm-3
1.6
1.4
1.2
1.0
rate
rate of
0.8-
0.6
0.4
0.2
0
the change in the amount or concentration of a particular
reactant or pr](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FgELOaDmqycJdQrDhLCpR_image_page_1.webp&w=2048&q=75)
The rate of reaction measures how quickly reactants transform into products over time. It's calculated as the change in amount or concentration divided by the time taken.
Rate = (Change in amount of reactants or products) ÷ (Time)
The standard units for rate of reaction are mol dm⁻³ s⁻¹, though slower reactions might use mol dm⁻³ min⁻¹ or mol dm⁻³ h⁻¹ instead. When we track a reaction like the isomerization of cyclopropane to propene, we can record how concentrations change over time.
Quick Tip Square brackets around a chemical formula (like [propene]) indicate concentration. This notation will appear frequently in your chemistry coursework!
As a reaction progresses, its rate typically changes because reactant concentrations decrease while product concentrations increase. This is why measuring rate at different time points gives us valuable information about reaction behavior.
![[propene] /mol dm-3
1.6
1.4
1.2
1.0
rate
rate of
0.8-
0.6
0.4
0.2
0
the change in the amount or concentration of a particular
reactant or pr](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FgELOaDmqycJdQrDhLCpR_image_page_2.webp&w=2048&q=75)
When measuring reaction rates, it's crucial to maintain a constant temperature throughout your experiment. Even small temperature changes can dramatically affect how fast a reaction proceeds.
For the cyclopropane example, we can calculate the average rate over the first 5 minutes Rate = Δ ÷ time = 0.27 ÷ 5 = 0.054 mol dm⁻³ min⁻¹
Notice on concentration-time graphs that curves typically become shallower over time, indicating the reaction is slowing down. The most accurate way to determine the rate at a specific moment is by drawing a tangent to the curve at that point.
Remember The smaller your time intervals for measurement, the more accurate your reaction rate calculations will be. This is especially important for fast reactions!
By analyzing these rates, you can understand exactly how reaction speed changes throughout the process, which is key information for controlling chemical reactions.
![[propene] /mol dm-3
1.6
1.4
1.2
1.0
rate
rate of
0.8-
0.6
0.4
0.2
0
the change in the amount or concentration of a particular
reactant or pr](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FgELOaDmqycJdQrDhLCpR_image_page_3.webp&w=2048&q=75)
Drawing tangents lets you find the instantaneous rate at any specific moment during a reaction. Here's how to do it
First, select a point on your graph and draw a straight line that just touches the curve at that point. Extend this tangent until it meets both axes, then calculate its gradient (slope).
For our cyclopropane example at 10 minutes, the slope calculation gives -6.67 × 10⁻⁴ mol dm⁻³ s⁻¹. The negative sign indicates that reactant concentration is decreasing over time.
This tangent method is powerful because it captures exactly how fast the reaction is proceeding at a single moment, rather than giving an average over time. You'll use this technique frequently in advanced chemistry courses.
Pro Technique When drawing tangents, make sure the angles between your line and the curve look similar on both sides—this ensures you've positioned the tangent correctly!
![[propene] /mol dm-3
1.6
1.4
1.2
1.0
rate
rate of
0.8-
0.6
0.4
0.2
0
the change in the amount or concentration of a particular
reactant or pr](/_next/image?url=https%3A%2F%2Fcontent-eu-central-1.knowunity.com%2FCONTENT%2FgELOaDmqycJdQrDhLCpR_image_page_4.webp&w=2048&q=75)
The final graph reveals something fascinating the rate of reaction is directly proportional to the concentration of cyclopropane. This is a key insight about this particular reaction.
This proportional relationship means that doubling the concentration of cyclopropane will double the reaction rate. Understanding these relationships helps chemists predict and control reactions in various applications.
This pattern isn't universal for all reactions—some have more complex relationships between concentration and rate. Learning to identify these patterns is an important skill in chemical kinetics.
Real-World Connection This concentration-rate relationship is why medications have specific dosages! Your body metabolizes substances at rates that depend on their concentration in your bloodstream.
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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Explore the key factors affecting reaction rates, including temperature, concentration, pressure, surface area, and catalysts. Understand collision theory and activation energy to grasp how these elements impact the speed of chemical reactions. This summary provides essential insights for students studying reaction kinetics.
ChemistryLearn about the reactivity and properties of metals, alkali metals, alkaline earth metals, and transition metals in the periodic table.
ChemistryThis note contains the summary of the topics redox reaction, electrochemistry, nuclear chemistry, and stoichiometry.
AP ChemistryLearn about Henry Moseley's contribution to the modern periodic table and the arrangement of elements based on atomic number and properties.
Chemistryionic and covalent compounds
ChemistryAn introduction to chemistry including the different branches of chemistry.
ChemistryApp 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
Dive into the world of reaction kinetics, where we explore how quickly chemical reactions happen and what affects their speed. Understanding reaction rates is key to predicting chemical behavior and is a fundamental concept in chemistry you'll use throughout your... Show more
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The rate of reaction measures how quickly reactants transform into products over time. It's calculated as the change in amount or concentration divided by the time taken.
Rate = (Change in amount of reactants or products) ÷ (Time)
The standard units for rate of reaction are mol dm⁻³ s⁻¹, though slower reactions might use mol dm⁻³ min⁻¹ or mol dm⁻³ h⁻¹ instead. When we track a reaction like the isomerization of cyclopropane to propene, we can record how concentrations change over time.
Quick Tip: Square brackets around a chemical formula (like [propene]) indicate concentration. This notation will appear frequently in your chemistry coursework!
As a reaction progresses, its rate typically changes because reactant concentrations decrease while product concentrations increase. This is why measuring rate at different time points gives us valuable information about reaction behavior.
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
When measuring reaction rates, it's crucial to maintain a constant temperature throughout your experiment. Even small temperature changes can dramatically affect how fast a reaction proceeds.
For the cyclopropane example, we can calculate the average rate over the first 5 minutes: Rate = Δ ÷ time = 0.27 ÷ 5 = 0.054 mol dm⁻³ min⁻¹
Notice on concentration-time graphs that curves typically become shallower over time, indicating the reaction is slowing down. The most accurate way to determine the rate at a specific moment is by drawing a tangent to the curve at that point.
Remember: The smaller your time intervals for measurement, the more accurate your reaction rate calculations will be. This is especially important for fast reactions!
By analyzing these rates, you can understand exactly how reaction speed changes throughout the process, which is key information for controlling chemical reactions.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Drawing tangents lets you find the instantaneous rate at any specific moment during a reaction. Here's how to do it:
First, select a point on your graph and draw a straight line that just touches the curve at that point. Extend this tangent until it meets both axes, then calculate its gradient (slope).
For our cyclopropane example at 10 minutes, the slope calculation gives -6.67 × 10⁻⁴ mol dm⁻³ s⁻¹. The negative sign indicates that reactant concentration is decreasing over time.
This tangent method is powerful because it captures exactly how fast the reaction is proceeding at a single moment, rather than giving an average over time. You'll use this technique frequently in advanced chemistry courses.
Pro Technique: When drawing tangents, make sure the angles between your line and the curve look similar on both sides—this ensures you've positioned the tangent correctly!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
The final graph reveals something fascinating: the rate of reaction is directly proportional to the concentration of cyclopropane. This is a key insight about this particular reaction.
This proportional relationship means that doubling the concentration of cyclopropane will double the reaction rate. Understanding these relationships helps chemists predict and control reactions in various applications.
This pattern isn't universal for all reactions—some have more complex relationships between concentration and rate. Learning to identify these patterns is an important skill in chemical kinetics.
Real-World Connection: This concentration-rate relationship is why medications have specific dosages! Your body metabolizes substances at rates that depend on their concentration in your bloodstream.
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.
0
Smart Tools NEW
Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
Explore the key factors affecting reaction rates, including temperature, concentration, pressure, surface area, and catalysts. Understand collision theory and activation energy to grasp how these elements impact the speed of chemical reactions. This summary provides essential insights for students studying reaction kinetics.
ChemistryLearn about the reactivity and properties of metals, alkali metals, alkaline earth metals, and transition metals in the periodic table.
ChemistryThis note contains the summary of the topics redox reaction, electrochemistry, nuclear chemistry, and stoichiometry.
AP ChemistryLearn about Henry Moseley's contribution to the modern periodic table and the arrangement of elements based on atomic number and properties.
Chemistryionic and covalent compounds
ChemistryAn introduction to chemistry including the different branches of chemistry.
ChemistryApp 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
Algebra
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