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Dec 25, 2025
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Understanding Reaction Rates in Higher Chemistry
S
sy7
@sy7_quyl
1 / 5
Controlling Reaction Rates
You already know the four main ways to speed up reactions: increase temperature, decrease particle size, increase concentration, and use a catalyst. These aren't just random facts - they're essential tools that industrial chemists use every day.
Collision theory explains why these methods work. Simply put, particles must crash into each other before any reaction can happen. The more collisions you get, the faster your reaction goes.
When you increase surface area by grinding up particles, you're giving more space for collisions to occur. Think of it like this: a whole sugar cube dissolves slowly, but granulated sugar disappears instantly because there's loads more surface exposed to the water.
Quick Check: Powdered magnesium reacts much faster with acid than magnesium ribbon because there are far more collision sites available.
Measuring Reaction Rates - Method A
Here's where chemistry gets practical - you can actually measure how fast reactions go by tracking volume changes over time. The data shows that ground chips (S) produce gas much faster than whole chips (L).
Looking at the numbers, ground chips had an average rate of 1.8 cm³/s in the first 20 seconds, whilst whole chips only managed 1.3 cm³/s. That's collision theory in action right there.
Notice how both reactions slow down over time? The ground chips dropped to just 0.2 cm³/s in the second interval whilst whole chips fell to 0.72 cm³/s. This happens because you're running out of reactants to collide.
Pro Tip: Always plot your results on a graph - it makes patterns much clearer than staring at tables of numbers.
Measuring Reaction Rates - Method B
Method B tracks the reaction by measuring mass loss instead of gas volume. The pattern's identical though - smaller particles react faster because there's more surface area for collisions.
Ground chips lost mass at 0.068 g/s initially, compared to 0.05 g/s for whole chips. By the second 20-second period, the ground chips had practically stopped reacting whilst whole chips were still going at 0.018 g/s.
This shows you something important: particle size doesn't just affect how fast a reaction starts - it completely changes the reaction profile. Smaller particles burn through reactants quickly then stop, whilst larger ones have a steadier, longer-lasting reaction.
Real World: This is why different grain sizes of gunpowder create different explosive effects in fireworks.
Concentration and Rate Calculations
Concentration affects reaction rates because more particles in the same space means more collisions. It's like a busy dance floor - the more crowded it gets, the more people bump into each other.
As reactions progress, they naturally slow down because you're converting reactants into products. Fewer reactant particles means fewer collisions, which means a slower rate. The graph always curves downwards for this reason.
You can calculate relative rate using the formula 1/time, which gives you the rate at one specific moment. This is different from average rate, which looks at change over a time period. Relative rate has units of s⁻¹, whilst average rate units depend on what you're measuring.
Exam Tip: Remember that relative rate = 1/time is only valid when comparing reactions that go to the same extent of completion.
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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❗️❗️⚠️
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Brad T
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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!
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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.
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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
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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
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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
Understanding Reaction Rates in Higher Chemistry
S
sy7
@sy7_quyl
Ever wondered why some chemical reactions happen in a flash whilst others take ages? Understanding how to control reaction rates is crucial for chemists - they need reactions fast enough to be profitable but not so quick they become dangerous... Show more
Controlling Reaction Rates
You already know the four main ways to speed up reactions: increase temperature, decrease particle size, increase concentration, and use a catalyst. These aren't just random facts - they're essential tools that industrial chemists use every day.
Collision theory explains why these methods work. Simply put, particles must crash into each other before any reaction can happen. The more collisions you get, the faster your reaction goes.
When you increase surface area by grinding up particles, you're giving more space for collisions to occur. Think of it like this: a whole sugar cube dissolves slowly, but granulated sugar disappears instantly because there's loads more surface exposed to the water.
Quick Check: Powdered magnesium reacts much faster with acid than magnesium ribbon because there are far more collision sites available.
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Measuring Reaction Rates - Method A
Here's where chemistry gets practical - you can actually measure how fast reactions go by tracking volume changes over time. The data shows that ground chips (S) produce gas much faster than whole chips (L).
Looking at the numbers, ground chips had an average rate of 1.8 cm³/s in the first 20 seconds, whilst whole chips only managed 1.3 cm³/s. That's collision theory in action right there.
Notice how both reactions slow down over time? The ground chips dropped to just 0.2 cm³/s in the second interval whilst whole chips fell to 0.72 cm³/s. This happens because you're running out of reactants to collide.
Pro Tip: Always plot your results on a graph - it makes patterns much clearer than staring at tables of numbers.
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Measuring Reaction Rates - Method B
Method B tracks the reaction by measuring mass loss instead of gas volume. The pattern's identical though - smaller particles react faster because there's more surface area for collisions.
Ground chips lost mass at 0.068 g/s initially, compared to 0.05 g/s for whole chips. By the second 20-second period, the ground chips had practically stopped reacting whilst whole chips were still going at 0.018 g/s.
This shows you something important: particle size doesn't just affect how fast a reaction starts - it completely changes the reaction profile. Smaller particles burn through reactants quickly then stop, whilst larger ones have a steadier, longer-lasting reaction.
Real World: This is why different grain sizes of gunpowder create different explosive effects in fireworks.
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Concentration and Rate Calculations
Concentration affects reaction rates because more particles in the same space means more collisions. It's like a busy dance floor - the more crowded it gets, the more people bump into each other.
As reactions progress, they naturally slow down because you're converting reactants into products. Fewer reactant particles means fewer collisions, which means a slower rate. The graph always curves downwards for this reason.
You can calculate relative rate using the formula 1/time, which gives you the rate at one specific moment. This is different from average rate, which looks at change over a time period. Relative rate has units of s⁻¹, whilst average rate units depend on what you're measuring.
Exam Tip: Remember that relative rate = 1/time is only valid when comparing reactions that go to the same extent of completion.
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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?
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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