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lia
09/12/2025
Chemistry
Acids and bases ~ Chemistry
372
•
9 Dec 2025
•
Understanding Acids, Bases, and Alkalis in Chemistry
lia
@liastudiess
1 / 4
What Makes Acids and Bases Special?
You encounter acids and bases every single day without realising it. When you bite into a lemon and scrunch up your face, that's because acids have a distinctly sour taste. Bases, on the other hand, taste bitter and feel soapy to touch.
Both acids and bases are corrosive, which means they can wear away other materials over time. This is why you should never touch strong acids or bases with your bare hands! They're also both able to conduct electricity, making them quite powerful substances.
The easiest way to tell them apart is using litmus paper. Acids turn blue litmus paper red, whilst bases turn red litmus paper blue. Think of it as a simple colour-coded test that scientists use all the time.
Quick Tip: Remember "A-R-B-B" - Acids turn litmus Red, Bases turn litmus Blue!
Understanding pH and Neutralisation
The pH scale runs from 1 to 14 and tells us how acidic or basic a substance is. Numbers 1-6 are acidic , 7 is neutral, and 8-14 are alkali . Pure water sits right in the middle at pH 7.
Acids are made of hydrogen ions, whilst alkalis (bases dissolved in water) contain hydroxide ions. When you mix an acid with an alkali, something magical happens - they cancel each other out! This process is called neutralisation.
The neutralisation reaction always follows the same pattern: Acid + Alkali → Salt + Water. It's like they're perfectly balanced opponents that create something completely harmless when they meet.
Remember: Strong acids have lots of hydrogen ions (concentrated), whilst weak acids have fewer hydrogen ions (dilute).
Acids and Bases in Your Daily Life
You're surrounded by acids without even knowing it! Vinegar contains acetic acid, lemon juice has citric acid, and your stomach acid is actually hydrochloric acid. Even fizzy drinks get their tang from carbonic acid, and car batteries use sulphuric acid for power.
Bases are just as common in your home. Baking soda, toothpaste, shampoo, and even indigestion tablets like Calpol and Nurofen are all basic substances. Oven cleaner is a particularly strong base, which is why it's so good at breaking down greasy, burnt-on food.
Scientists use indicators to identify whether something is acidic or basic. These clever substances change colour depending on the pH - turning red for acids and blue for alkalis. It's like having a chemical traffic light system!
Cool Fact: Your stomach produces about 2 litres of hydrochloric acid every day to help digest your food!
Mastering the pH Scale
Think of the pH scale as a sliding scale of chemical strength. The numbers 1-3 represent strong acids like the hydrochloric acid in your stomach or the sulphuric acid in car batteries. Numbers 4-6 are weak acids like the citric acid in oranges.
At pH 7, substances are perfectly neutral - neither acidic nor basic. Pure water is the best example of this. Once you move past 7, you enter alkali territory.
Numbers 8-10 represent weak alkalis like baking soda and toothpaste, whilst 11-14 are the strong alkalis like oven cleaner and drain unblocker. The further you move from 7 in either direction, the more extreme the substance becomes.
Test Tip: Remember that acids have a pH less than 7, and alkalis have a pH greater than 7!
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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.
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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
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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
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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
Understanding Acids, Bases, and Alkalis in Chemistry
lia
@liastudiess
Ever wondered why lemon juice tastes sour or why soap feels slippery? It's all about acids and bases! These chemical substances are everywhere around us, from the food we eat to the cleaning products we use.
What Makes Acids and Bases Special?
You encounter acids and bases every single day without realising it. When you bite into a lemon and scrunch up your face, that's because acids have a distinctly sour taste. Bases, on the other hand, taste bitter and feel soapy to touch.
Both acids and bases are corrosive, which means they can wear away other materials over time. This is why you should never touch strong acids or bases with your bare hands! They're also both able to conduct electricity, making them quite powerful substances.
The easiest way to tell them apart is using litmus paper. Acids turn blue litmus paper red, whilst bases turn red litmus paper blue. Think of it as a simple colour-coded test that scientists use all the time.
Quick Tip: Remember "A-R-B-B" - Acids turn litmus Red, Bases turn litmus Blue!
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Improve your grades
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By signing up you accept Terms of Service and Privacy Policy
Understanding pH and Neutralisation
The pH scale runs from 1 to 14 and tells us how acidic or basic a substance is. Numbers 1-6 are acidic , 7 is neutral, and 8-14 are alkali . Pure water sits right in the middle at pH 7.
Acids are made of hydrogen ions, whilst alkalis (bases dissolved in water) contain hydroxide ions. When you mix an acid with an alkali, something magical happens - they cancel each other out! This process is called neutralisation.
The neutralisation reaction always follows the same pattern: Acid + Alkali → Salt + Water. It's like they're perfectly balanced opponents that create something completely harmless when they meet.
Remember: Strong acids have lots of hydrogen ions (concentrated), whilst weak acids have fewer hydrogen ions (dilute).
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Improve your grades
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Acids and Bases in Your Daily Life
You're surrounded by acids without even knowing it! Vinegar contains acetic acid, lemon juice has citric acid, and your stomach acid is actually hydrochloric acid. Even fizzy drinks get their tang from carbonic acid, and car batteries use sulphuric acid for power.
Bases are just as common in your home. Baking soda, toothpaste, shampoo, and even indigestion tablets like Calpol and Nurofen are all basic substances. Oven cleaner is a particularly strong base, which is why it's so good at breaking down greasy, burnt-on food.
Scientists use indicators to identify whether something is acidic or basic. These clever substances change colour depending on the pH - turning red for acids and blue for alkalis. It's like having a chemical traffic light system!
Cool Fact: Your stomach produces about 2 litres of hydrochloric acid every day to help digest your food!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Mastering the pH Scale
Think of the pH scale as a sliding scale of chemical strength. The numbers 1-3 represent strong acids like the hydrochloric acid in your stomach or the sulphuric acid in car batteries. Numbers 4-6 are weak acids like the citric acid in oranges.
At pH 7, substances are perfectly neutral - neither acidic nor basic. Pure water is the best example of this. Once you move past 7, you enter alkali territory.
Numbers 8-10 represent weak alkalis like baking soda and toothpaste, whilst 11-14 are the strong alkalis like oven cleaner and drain unblocker. The further you move from 7 in either direction, the more extreme the substance becomes.
Test Tip: Remember that acids have a pH less than 7, and alkalis have a pH greater than 7!
We thought you’d never ask...
What is the Knowunity AI companion?
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.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
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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Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.9/5
App Store
4.8/5
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