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How Concentration Affects Rate of Reaction
Ever wondered why some chemical reactions happen in the blink of an eye while others take ages? The answer often lies in concentration. When we increase the concentration of reactants, more particles are packed into the same space, creating more collisions between particles.
In this practical, you'll measure how quickly a reaction happens at different concentrations. You might use a gas syringe or an inverted measuring cylinder to collect gas produced when acid reacts with magnesium ribbon. Alternatively, you might time how quickly a cross disappears when sodium thiosulfate reacts with hydrochloric acid.
The results consistently show that higher concentrations lead to faster reaction rates. This happens because more particles in the same volume means more frequent collisions between reactants.
Top Tip: When answering exam questions about this practical, focus on potential errors like timing issues or not controlling variables properly. Remember that everything except concentration should remain constant!
Your measurements need to be precise - whether you're recording gas volume or timing how quickly a solution becomes cloudy enough to obscure a cross drawn under a flask.
Identifying Substances Using Chromatography
Chromatography might sound complicated, but it's actually a brilliant technique for separating and identifying different substances in a mixture. Think of it as letting substances race up paper at different speeds!
In this practical, you'll place small spots of different substances (like food colourings) on a pencil line near the bottom of chromatography paper. When dipped in a solvent like water, the substances travel upward at different rates depending on their properties.
The key measurement you'll make is called the Rf value, which is simply how far the substance traveled divided by how far the solvent traveled. Each substance has a unique Rf value, which makes this a great way to identify unknown compounds.
Remember: Always draw your start line in pencil, not pen! Pen ink would dissolve and run in the solvent, ruining your results.
When analysing your chromatogram, look carefully at which spots from your unknown mixture match the positions of known substances. This tells you exactly what's in your mystery mixture!
Purifying and Testing Water
Clean water is something many of us take for granted, but how do we actually make water safe to drink? This practical shows you how water purification works through distillation.
You'll start with salty or contaminated water, then heat it so the water evaporates (turns to steam) while the impurities stay behind. The pure water vapour then cools and condenses back into liquid water that's now free of dissolved solids.
Testing is an important part of water analysis. Pure water should have a pH of exactly 7 and boil at precisely 100°C (at standard pressure). Any deviation might indicate impurities.
Interesting Fact: While distillation produces very pure water, it's rarely used for large-scale drinking water production because heating so much water would be incredibly expensive!
In the exam, be prepared to explain not just how distillation works, but also its limitations. For instance, some water always remains in the apparatus, and the energy costs make it impractical for treating large volumes of water.
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This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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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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very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
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I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
Mastering Chemistry Paper 2: Essential Required Practicals
Chemistry practicals are a crucial part of your GCSE studies, helping you see scientific principles in action. These hands-on experiments demonstrate important concepts like reaction rates, substance identification, and water purification that you'll need to understand for your exams.
How Concentration Affects Rate of Reaction
Ever wondered why some chemical reactions happen in the blink of an eye while others take ages? The answer often lies in concentration. When we increase the concentration of reactants, more particles are packed into the same space, creating more collisions between particles.
In this practical, you'll measure how quickly a reaction happens at different concentrations. You might use a gas syringe or an inverted measuring cylinder to collect gas produced when acid reacts with magnesium ribbon. Alternatively, you might time how quickly a cross disappears when sodium thiosulfate reacts with hydrochloric acid.
The results consistently show that higher concentrations lead to faster reaction rates. This happens because more particles in the same volume means more frequent collisions between reactants.
Top Tip: When answering exam questions about this practical, focus on potential errors like timing issues or not controlling variables properly. Remember that everything except concentration should remain constant!
Your measurements need to be precise - whether you're recording gas volume or timing how quickly a solution becomes cloudy enough to obscure a cross drawn under a flask.
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Identifying Substances Using Chromatography
Chromatography might sound complicated, but it's actually a brilliant technique for separating and identifying different substances in a mixture. Think of it as letting substances race up paper at different speeds!
In this practical, you'll place small spots of different substances (like food colourings) on a pencil line near the bottom of chromatography paper. When dipped in a solvent like water, the substances travel upward at different rates depending on their properties.
The key measurement you'll make is called the Rf value, which is simply how far the substance traveled divided by how far the solvent traveled. Each substance has a unique Rf value, which makes this a great way to identify unknown compounds.
Remember: Always draw your start line in pencil, not pen! Pen ink would dissolve and run in the solvent, ruining your results.
When analysing your chromatogram, look carefully at which spots from your unknown mixture match the positions of known substances. This tells you exactly what's in your mystery mixture!
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Purifying and Testing Water
Clean water is something many of us take for granted, but how do we actually make water safe to drink? This practical shows you how water purification works through distillation.
You'll start with salty or contaminated water, then heat it so the water evaporates (turns to steam) while the impurities stay behind. The pure water vapour then cools and condenses back into liquid water that's now free of dissolved solids.
Testing is an important part of water analysis. Pure water should have a pH of exactly 7 and boil at precisely 100°C (at standard pressure). Any deviation might indicate impurities.
Interesting Fact: While distillation produces very pure water, it's rarely used for large-scale drinking water production because heating so much water would be incredibly expensive!
In the exam, be prepared to explain not just how distillation works, but also its limitations. For instance, some water always remains in the apparatus, and the energy costs make it impractical for treating large volumes of water.
We thought you’d never ask...
What is the Knowunity AI companion?
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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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
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
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
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
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
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 apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user