Zakon o ohranitvi mase je eno najbolj pomembnih pravil v... Show more
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Updated Apr 15, 2026
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Kaj je Zakon o Ohranitvi Mase?
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Osnove zakona o ohranitvi mase
Predstavljaj si kemijsko reakcijo kot preurejanje kock Lego. Če imaš na začetku 50 gramov kock in iz njih zgradiš hišo, bo hiša še vedno tehtala 50 gramov. V kemiji je enako - atomi se samo preuredijo, ne izginejo!
Reaktanti so snovi, s katerimi začneš reakcijo (kot razmetane kocke). Produkti so snovi, ki nastanejo (kot zgrajena hiša). Zakon o ohranitvi mase pravi, da je masa reaktantov vedno enaka masi produktov.
To pravilo je odkril Antoine Lavoisier, ki mu pravimo "oče sodobne kemije". Dobro si zapomni to ime za test!
💡 Zapomniti si moraš: Snov se med reakcijo samo preuredi, nikoli ne izgine ali nastane iz nič.
Kako deluje v praksi
Ko gledaš kemijsko enačbo, moraš preveriti, ali je na obeh straneh enako število atomov vsakega elementa. Vzemi nastanek vode: 2H₂ + O₂ → 2H₂O.
Na levi strani imaš 4 atome vodika in 2 atoma kisika. Na desni strani prav tako 4 atome vodika (v dveh molekulah vode) in 2 atoma kisika. Ker se število atomov ne spremeni, se tudi masa ne.
Če bi imel 4 g vodika in 32 g kisika, bi nastalo natanko 36 g vode. Formula je preprosta: m(reaktanti) = m(produkti).
💡 Hitri trik: Vedno preštej atome na obeh straneh enačbe - če se ujemajo, se bo ujemala tudi masa!
Reševanje nalog korak za korak
Pri računskih primerih sledi vedno istemu postopku. Če 56 g železa reagira z 24 g kisika in nastane rja, koliko rje nastane?
Najprej zapiši podatke: reaktanta sta železo (56 g) in kisik (24 g), produkt je rja. Uporabi zakon ohranitvi mase: masa reaktantov = masa produktov.
Preprosto sešteješ: 56 g + 24 g = 80 g. Torej nastane 80 g rje. Če imaš obratno nalogo in poznaš maso enega produkta, preprosto odšteješ od skupne mase reaktantov.
💡 Za teste: Vedno preveri, ali si upošteval vse snovi - tudi tiste, ki jih nisi eksplicitno omenil!
Pozor na past - odprti in zaprti sistemi
Največja napaka pri ohranitvi mase je, da pozabiš na plinske snovi! V odprtem sistemu (npr. odprta čaša) lahko plini uidejo ali pridejo iz zraka.
Če meša kis in sodo bikarbono v odprti čaši, bo masa na koncu manjša, ker ogljikov dioksid uide. Pri gorenju lesa se masa navidezno poveča, ker les reagira s kisikom iz zraka, ki ga nisi stehtал na začetku.
V zaprtem sistemu (zaprta posoda) masa ostane vedno enaka, ker nobena snov ne more uiti. Če bi reakcijo kisa in sode naredil v zaprti plastenki, bi se ta samo napihnila, ampak skupna masa bi ostala enaka.
💡 Ključno vprašanje: Ali lahko katera koli snov uide iz sistema ali pride vanj? To ti pove, zakaj se masa navidezno spremeni.
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4.7/5
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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 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
Kaj je Zakon o Ohranitvi Mase?
Zakon o ohranitvi mase je eno najbolj pomembnih pravil v kemiji, ki ga boš potreboval pri vseh kemijskih reakcijah. To pravilo ti pove, da se snovi med kemijsko reakcijo ne morejo kar pojaviti iz nič ali popolnoma izginiti - samo... Show more
Osnove zakona o ohranitvi mase
Predstavljaj si kemijsko reakcijo kot preurejanje kock Lego. Če imaš na začetku 50 gramov kock in iz njih zgradiš hišo, bo hiša še vedno tehtala 50 gramov. V kemiji je enako - atomi se samo preuredijo, ne izginejo!
Reaktanti so snovi, s katerimi začneš reakcijo (kot razmetane kocke). Produkti so snovi, ki nastanejo (kot zgrajena hiša). Zakon o ohranitvi mase pravi, da je masa reaktantov vedno enaka masi produktov.
To pravilo je odkril Antoine Lavoisier, ki mu pravimo "oče sodobne kemije". Dobro si zapomni to ime za test!
💡 Zapomniti si moraš: Snov se med reakcijo samo preuredi, nikoli ne izgine ali nastane iz nič.
Sign up to see the contentIt's free!
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Join milions of students
Kako deluje v praksi
Ko gledaš kemijsko enačbo, moraš preveriti, ali je na obeh straneh enako število atomov vsakega elementa. Vzemi nastanek vode: 2H₂ + O₂ → 2H₂O.
Na levi strani imaš 4 atome vodika in 2 atoma kisika. Na desni strani prav tako 4 atome vodika (v dveh molekulah vode) in 2 atoma kisika. Ker se število atomov ne spremeni, se tudi masa ne.
Če bi imel 4 g vodika in 32 g kisika, bi nastalo natanko 36 g vode. Formula je preprosta: m(reaktanti) = m(produkti).
💡 Hitri trik: Vedno preštej atome na obeh straneh enačbe - če se ujemajo, se bo ujemala tudi masa!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Reševanje nalog korak za korak
Pri računskih primerih sledi vedno istemu postopku. Če 56 g železa reagira z 24 g kisika in nastane rja, koliko rje nastane?
Najprej zapiši podatke: reaktanta sta železo (56 g) in kisik (24 g), produkt je rja. Uporabi zakon ohranitvi mase: masa reaktantov = masa produktov.
Preprosto sešteješ: 56 g + 24 g = 80 g. Torej nastane 80 g rje. Če imaš obratno nalogo in poznaš maso enega produkta, preprosto odšteješ od skupne mase reaktantov.
💡 Za teste: Vedno preveri, ali si upošteval vse snovi - tudi tiste, ki jih nisi eksplicitno omenil!
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
Pozor na past - odprti in zaprti sistemi
Največja napaka pri ohranitvi mase je, da pozabiš na plinske snovi! V odprtem sistemu (npr. odprta čaša) lahko plini uidejo ali pridejo iz zraka.
Če meša kis in sodo bikarbono v odprti čaši, bo masa na koncu manjša, ker ogljikov dioksid uide. Pri gorenju lesa se masa navidezno poveča, ker les reagira s kisikom iz zraka, ki ga nisi stehtал na začetku.
V zaprtem sistemu (zaprta posoda) masa ostane vedno enaka, ker nobena snov ne more uiti. Če bi reakcijo kisa in sode naredil v zaprti plastenki, bi se ta samo napihnila, ampak skupna masa bi ostala enaka.
💡 Ključno vprašanje: Ali lahko katera koli snov uide iz sistema ali pride vanj? To ti pove, zakaj se masa navidezno spremeni.
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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Students love us — and so will you.
4.6/5
App Store
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