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Organisms respond to changes in their internal and external environments (a-level only)
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Britain & the wider world: 1745 -1901
1l the quest for political stability: germany, 1871-1991
The cold war
Inter-war germany
Medieval period: 1066 -1509
2d religious conflict and the church in england, c1529-c1570
2o democracy and nazism: germany, 1918-1945
1f industrialisation and the people: britain, c1783-1885
1c the tudors: england, 1485-1603
2m wars and welfare: britain in transition, 1906-1957
World war two & the holocaust
2n revolution and dictatorship: russia, 1917-1953
2s the making of modern britain, 1951-2007
World war one
Britain: 1509 -1745
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1,060
•
7 Dec 2025
•
Lena
@lena_ftpy
Chemistry practicals can seem daunting, but these four core experiments... Show more
Ever wondered how table salt is actually made in a lab? This practical shows you how to create pure crystals from scratch using a simple acid-base reaction. You'll be combining sulphuric acid with copper oxide to produce beautiful blue copper sulphate crystals.
The process is quite straightforward: heat dilute sulphuric acid gently, then add copper oxide powder until no more fizzing occurs (this means all the acid has reacted). Filter out the leftover copper oxide, then evaporate your solution slowly using a water bath until crystals begin forming.
The key to success is patience during the crystallisation process. Leave your solution in a cool place for at least 24 hours to get proper crystal formation. Pat them dry carefully with filter paper, and you'll have created your first pure salt sample.
Top tip: Add the copper oxide in excess - you'll know you've added enough when the fizzing stops completely. This ensures all your acid has reacted.
Titration might sound complex, but it's basically just finding out exactly how much acid you need to neutralise a base. You're playing detective to discover the unknown concentration of sulphuric acid using sodium hydroxide solution.
Your main tools are a burette (the tall tube with measurements) and a pipette for precise measuring. Add phenolphthalein indicator to your sodium hydroxide - it'll turn pink and act as your colour-change signal. Slowly drip acid from the burette whilst swirling your flask.
The magic moment is the end point - when the solution suddenly changes from pink to colourless. This tells you the acid and base have perfectly neutralised each other. Record your measurements and repeat until you get concordant results (within 0.1 cm³ of each other).
Remember: Always read the burette from the bottom of the meniscus and add acid drop-by-drop near the end point to avoid overshooting.
Electrolysis is like using electricity to break apart compounds - think of it as chemical demolition! You'll investigate what happens when electric current passes through aqueous solutions using carbon electrodes.
Set up your circuit with carbon rods as inert electrodes in solutions of copper chloride and sodium chloride. When you switch on the 4V power supply, chemical magic happens. At the positive electrode (anode), chlorine gas bubbles off, whilst at the negative electrode (cathode), different products form depending on your solution.
With copper chloride, you'll see brown copper metal coating the negative electrode. Sodium chloride produces hydrogen gas instead. Use blue litmus paper held with forceps to test for the gases - chlorine will bleach it white.
Safety first: Ensure good ventilation because chlorine gas is toxic. Never let the electrodes touch each other or you'll short-circuit your setup.
This practical lets you explore exothermic reactions by measuring temperature changes when acids and alkalis react. You're investigating how the amount of reactants affects the heat energy released during neutralisation.
Use polystyrene cups as your reaction vessel - they're excellent insulators that prevent heat loss to surroundings. Start with 25 cm³ of hydrochloric acid, measure its temperature, then gradually add 5 cm³ portions of sodium hydroxide solution.
Stir gently with your thermometer through the lid hole and record the maximum temperature after each addition. You'll notice the temperature rises as more alkali neutralises the acid, reaching a peak before dropping again when excess alkali cools the mixture.
Key point: Record temperatures quickly after mixing and keep stirring gently for accurate readings. The polystyrene cup acts like a calorimeter to minimise heat loss.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and 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
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
Lena
@lena_ftpy
Chemistry practicals can seem daunting, but these four core experiments are your gateway to understanding how chemical reactions work in real life. From making crystals to exploring electrolysis, these practicals give you hands-on experience with the fundamental processes that power... Show more
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Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Ever wondered how table salt is actually made in a lab? This practical shows you how to create pure crystals from scratch using a simple acid-base reaction. You'll be combining sulphuric acid with copper oxide to produce beautiful blue copper sulphate crystals.
The process is quite straightforward: heat dilute sulphuric acid gently, then add copper oxide powder until no more fizzing occurs (this means all the acid has reacted). Filter out the leftover copper oxide, then evaporate your solution slowly using a water bath until crystals begin forming.
The key to success is patience during the crystallisation process. Leave your solution in a cool place for at least 24 hours to get proper crystal formation. Pat them dry carefully with filter paper, and you'll have created your first pure salt sample.
Top tip: Add the copper oxide in excess - you'll know you've added enough when the fizzing stops completely. This ensures all your acid has reacted.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Titration might sound complex, but it's basically just finding out exactly how much acid you need to neutralise a base. You're playing detective to discover the unknown concentration of sulphuric acid using sodium hydroxide solution.
Your main tools are a burette (the tall tube with measurements) and a pipette for precise measuring. Add phenolphthalein indicator to your sodium hydroxide - it'll turn pink and act as your colour-change signal. Slowly drip acid from the burette whilst swirling your flask.
The magic moment is the end point - when the solution suddenly changes from pink to colourless. This tells you the acid and base have perfectly neutralised each other. Record your measurements and repeat until you get concordant results (within 0.1 cm³ of each other).
Remember: Always read the burette from the bottom of the meniscus and add acid drop-by-drop near the end point to avoid overshooting.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Electrolysis is like using electricity to break apart compounds - think of it as chemical demolition! You'll investigate what happens when electric current passes through aqueous solutions using carbon electrodes.
Set up your circuit with carbon rods as inert electrodes in solutions of copper chloride and sodium chloride. When you switch on the 4V power supply, chemical magic happens. At the positive electrode (anode), chlorine gas bubbles off, whilst at the negative electrode (cathode), different products form depending on your solution.
With copper chloride, you'll see brown copper metal coating the negative electrode. Sodium chloride produces hydrogen gas instead. Use blue litmus paper held with forceps to test for the gases - chlorine will bleach it white.
Safety first: Ensure good ventilation because chlorine gas is toxic. Never let the electrodes touch each other or you'll short-circuit your setup.
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
This practical lets you explore exothermic reactions by measuring temperature changes when acids and alkalis react. You're investigating how the amount of reactants affects the heat energy released during neutralisation.
Use polystyrene cups as your reaction vessel - they're excellent insulators that prevent heat loss to surroundings. Start with 25 cm³ of hydrochloric acid, measure its temperature, then gradually add 5 cm³ portions of sodium hydroxide solution.
Stir gently with your thermometer through the lid hole and record the maximum temperature after each addition. You'll notice the temperature rises as more alkali neutralises the acid, reaching a peak before dropping again when excess alkali cools the mixture.
Key point: Record temperatures quickly after mixing and keep stirring gently for accurate readings. The polystyrene cup acts like a calorimeter to minimise heat loss.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and 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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Transform this note into: ✓ 50+ Practice Questions ✓ Interactive Flashcards ✓ Full Mock Exam ✓ Essay Outlines
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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
Sociology