Koncentrácia roztokov je základná téma v chémii, ktorá ti pomôže... Show more
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Updated Apr 26, 2026
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Jak vypočítať a chápať koncentrácie roztokov
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Čo je koncentrácia a základné pojmy
Predstav si, že miešaš ovocný sirup s vodou. Koncentrácia ti povie, koľko sirupu je v tvojom nápoji. V chémii je to rovnaké - hovorí nám, koľko rozpustenej látky máme v roztoku.
Roztok sa skladá z dvoch častí: rozpúšťadla (väčšinou voda) a rozpustenej látky (napríklad soľ alebo cukor). Keď ich zmiešaš, dostaneš homogénnu zmes - vyzerá ako jedna látka.
Pamätaj si základnú rovnicu: hmotnosť roztoku = hmotnosť rozpúšťadla + hmotnosť rozpustenej látky. Toto ti pomôže pri všetkých výpočtoch!
Tip: Vždy si v zadaní najprv označ, čo je rozpúšťadlo, čo rozpustená látka a čo celý roztok.
Hmotnostný a objemový zlomok
Hmotnostný zlomok (w) je najjednoduchší spôsob vyjadrenia koncentrácie. Vzorec je: w = hmotnosť rozpustenej látky / hmotnosť roztoku. Výsledok je číslo bez jednotky, často v percentách.
Príklad: 10 g soli + 90 g vody = 100 g roztoku. w = 10g/100g = 0,1 = 10%.
Objemový zlomok (φ) funguje podobne, len s objemami: φ = objem rozpustenej látky / objem roztoku. Používa sa hlavne pre kvapaliny, ako alkohol vo víne.
Pozor: Pri objemoch sa nesčítavajú vždy presne , ale pre naše výpočty to predpokladáme.
Látková koncentrácia
Látková koncentrácia (c) je najdôležitejšia v chémii, pretože pracuje s mólmi. Vzorec: c = látkové množstvo / objem roztoku (v litroch). Jednotka je mol/L.
Najprv musíš vypočítať látkové množstvo: n = hmotnosť / molárna hmotnosť. Molárnu hmotnosť nájdeš v periodickej tabuľke.
Príklad: 11,7 g NaCl v 200 mL roztoku. Molárna hmotnosť NaCl ≈ 58,5 g/mol. n = 11,7g / 58,5g/mol = 0,2 mol. c = 0,2 mol / 0,2 L = 1 mol/L.
Nezabudni: Objem musí byť v litroch! 200 mL = 0,2 L.
Riešené príklady krok za krokom
Tu sú typické príklady zo skúšok:
Príklad 1: 25 g cukru + 225 g vody. Celková hmotnosť = 250 g. w = 25g/250g = 0,1 = 10%.
Príklad 2: Dezinfekcia "70% obj." v 0,5 L fľaši. Objem alkoholu = 0,7 × 500 mL = 350 mL.
Príklad 3: 8 g NaOH v 200 mL roztoku . n = 8g/40g/mol = 0,2 mol. c = 0,2 mol/0,2 L = 1 mol/L.
Stratégia: Vždy si napíš, čo máš dané a čo hľadáš, potom vyber správny vzorec.
Praktické tipy a časté chyby
Jednotky sú kľúčové! Skontroluj si ich pred každým výpočtom. 1 L = 1000 mL, 1 kg = 1000 g.
Percentá: Vždy ich preveď na desatinné číslo delením 100. Takže 25% = 0,25.
Molárna hmotnosť: Pre jednoatomové látky ju nájdeš priamo v periodickej tabuľke. Pre molekuly (ako NaCl, H₂SO₄) spočítaj atómové hmotnosti všetkých atómov.
Pozor na slovíčka: Ak zadanie hovorí "doplnili objem na 250 mL", znamená to, že celý roztok má 250 mL, nie že si pridal 250 mL vody!
Pre skúšku: Nezabudni na jednotky vo výsledku a vždy skontroluj, či ti vyšiel rozumný výsledek.
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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
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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
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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 Knowunity AI. 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 Knowunity AI. 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
Jak vypočítať a chápať koncentrácie roztokov
Koncentrácia roztokov je základná téma v chémii, ktorá ti pomôže pochopiť, ako "silné" alebo "slabé" sú tvoje roztoky. Je to ako s čajom - môžeš mať veľmi sladký (vysoká koncentrácia cukru) alebo nesladký (nízka koncentrácia).
Čo je koncentrácia a základné pojmy
Predstav si, že miešaš ovocný sirup s vodou. Koncentrácia ti povie, koľko sirupu je v tvojom nápoji. V chémii je to rovnaké - hovorí nám, koľko rozpustenej látky máme v roztoku.
Roztok sa skladá z dvoch častí: rozpúšťadla (väčšinou voda) a rozpustenej látky (napríklad soľ alebo cukor). Keď ich zmiešaš, dostaneš homogénnu zmes - vyzerá ako jedna látka.
Pamätaj si základnú rovnicu: hmotnosť roztoku = hmotnosť rozpúšťadla + hmotnosť rozpustenej látky. Toto ti pomôže pri všetkých výpočtoch!
Tip: Vždy si v zadaní najprv označ, čo je rozpúšťadlo, čo rozpustená látka a čo celý roztok.
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Hmotnostný a objemový zlomok
Hmotnostný zlomok (w) je najjednoduchší spôsob vyjadrenia koncentrácie. Vzorec je: w = hmotnosť rozpustenej látky / hmotnosť roztoku. Výsledok je číslo bez jednotky, často v percentách.
Príklad: 10 g soli + 90 g vody = 100 g roztoku. w = 10g/100g = 0,1 = 10%.
Objemový zlomok (φ) funguje podobne, len s objemami: φ = objem rozpustenej látky / objem roztoku. Používa sa hlavne pre kvapaliny, ako alkohol vo víne.
Pozor: Pri objemoch sa nesčítavajú vždy presne , ale pre naše výpočty to predpokladáme.
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Látková koncentrácia
Látková koncentrácia (c) je najdôležitejšia v chémii, pretože pracuje s mólmi. Vzorec: c = látkové množstvo / objem roztoku (v litroch). Jednotka je mol/L.
Najprv musíš vypočítať látkové množstvo: n = hmotnosť / molárna hmotnosť. Molárnu hmotnosť nájdeš v periodickej tabuľke.
Príklad: 11,7 g NaCl v 200 mL roztoku. Molárna hmotnosť NaCl ≈ 58,5 g/mol. n = 11,7g / 58,5g/mol = 0,2 mol. c = 0,2 mol / 0,2 L = 1 mol/L.
Nezabudni: Objem musí byť v litroch! 200 mL = 0,2 L.
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Riešené príklady krok za krokom
Tu sú typické príklady zo skúšok:
Príklad 1: 25 g cukru + 225 g vody. Celková hmotnosť = 250 g. w = 25g/250g = 0,1 = 10%.
Príklad 2: Dezinfekcia "70% obj." v 0,5 L fľaši. Objem alkoholu = 0,7 × 500 mL = 350 mL.
Príklad 3: 8 g NaOH v 200 mL roztoku . n = 8g/40g/mol = 0,2 mol. c = 0,2 mol/0,2 L = 1 mol/L.
Stratégia: Vždy si napíš, čo máš dané a čo hľadáš, potom vyber správny vzorec.
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Praktické tipy a časté chyby
Jednotky sú kľúčové! Skontroluj si ich pred každým výpočtom. 1 L = 1000 mL, 1 kg = 1000 g.
Percentá: Vždy ich preveď na desatinné číslo delením 100. Takže 25% = 0,25.
Molárna hmotnosť: Pre jednoatomové látky ju nájdeš priamo v periodickej tabuľke. Pre molekuly (ako NaCl, H₂SO₄) spočítaj atómové hmotnosti všetkých atómov.
Pozor na slovíčka: Ak zadanie hovorí "doplnili objem na 250 mL", znamená to, že celý roztok má 250 mL, nie že si pridal 250 mL vody!
Pre skúšku: Nezabudni na jednotky vo výsledku a vždy skontroluj, či ti vyšiel rozumný výsledek.
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
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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4.7/5
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 Knowunity AI. 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 Knowunity AI. 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