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120
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Dec 10, 2025
•
Florence Thomas
@florencethomas_cxht
Mass spectrometry is a powerful analytical technique that scientists use... Show more
Ever wondered how scientists identify mystery substances? Mass spectrometry is like a molecular fingerprinting system that reveals exactly what's in a sample. The process starts by turning particles into ions (charged particles), then accelerating and deflecting them through the instrument.
The key to understanding mass spectrometry lies in the mass-to-charge ratio . Heavier isotopes have larger m/z values, so they follow wider curved paths when deflected. Since most ions carry a 1+ charge, the separation mainly depends on their mass.
Here's something interesting: if an ion picks up a 2+ charge instead of 1+, it gets deflected more because its m/z ratio is halved. The abundance stays the same, but the signal appears at a different position on the spectrum.
Quick Tip: Remember that doubling the charge halves the m/z ratio - this often catches students out in exam questions!
Sometimes you'll need to work backwards from the average relative atomic mass to find isotope percentages. This is easier than it looks once you know the method. Take bromine with isotopes of mass 79 and 81, and an average atomic mass of 79.908.
Set up the equation: if x% is ⁷⁹Br, then % must be ⁸¹Br. So: 79x + 81 = 7990.8. Expanding this gives: 79x + 8100 - 81x = 7990.8, which simplifies to -2x = -109.2.
Solving gives x = 54.6, meaning ⁷⁹Br is 54.6% and ⁸¹Br is 45.4%. The key is setting up the algebra correctly and remembering that percentages must add up to 100.
Exam Hack: Always check your percentages add to 100% - it's an instant way to spot calculation errors!
Relative isotopic mass compares the mass of one specific isotope to 1/12th of a carbon-12 atom. Think of carbon-12 as the universal reference point - like using metres to measure length. Relative atomic mass is the weighted average of all isotopes of an element.
Relative formula mass (RFM) is simply the sum of all atomic masses in a compound. For NH₃, you add nitrogen (14) plus three hydrogens (1+1+1) to get 17. For more complex compounds like Al₂(SO₄)₃, count each atom carefully: 2 aluminium, 3 sulphur, and 12 oxygen atoms.
Hydrated compounds like CuSO₄·5H₂O include water molecules in the calculation. The dot means the water is loosely attached, but you still count all the atoms when calculating the RFM.
Memory Trick: Write out each atom individually when calculating RFM - it prevents you from missing atoms in brackets!
Time of flight spectroscopy is the most common type of mass spectrometry you'll encounter. The entire apparatus operates under vacuum to prevent ions colliding with air molecules, which would mess up the results.
The process has three main stages: ionisation, acceleration, and ion drift. During ionisation, the sample dissolves in a volatile solvent and gets forced through a needle connected to high voltage. This creates tiny charged droplets that eventually become single positive ions.
All ions receive the same kinetic energy during acceleration, but heavier particles move slower than lighter ones. As ions travel down the flight tube, they separate based on their speed. The detector measures their arrival time and converts this into electrical signals.
Finally, a computer processes these signals to generate a mass spectrum - essentially a graph showing which masses are present and in what amounts. The whole system works because lighter ions reach the detector first.
Real-World Connection: Mass spectrometry is used everywhere from drug testing in sports to identifying explosives at airports!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the 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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
Florence Thomas
@florencethomas_cxht
Mass spectrometry is a powerful analytical technique that scientists use to identify unknown compounds and determine the composition of elements. It works by turning particles into ions, accelerating them, and measuring how they deflect based on their mass-to-charge ratio.
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Ever wondered how scientists identify mystery substances? Mass spectrometry is like a molecular fingerprinting system that reveals exactly what's in a sample. The process starts by turning particles into ions (charged particles), then accelerating and deflecting them through the instrument.
The key to understanding mass spectrometry lies in the mass-to-charge ratio . Heavier isotopes have larger m/z values, so they follow wider curved paths when deflected. Since most ions carry a 1+ charge, the separation mainly depends on their mass.
Here's something interesting: if an ion picks up a 2+ charge instead of 1+, it gets deflected more because its m/z ratio is halved. The abundance stays the same, but the signal appears at a different position on the spectrum.
Quick Tip: Remember that doubling the charge halves the m/z ratio - this often catches students out in exam questions!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Sometimes you'll need to work backwards from the average relative atomic mass to find isotope percentages. This is easier than it looks once you know the method. Take bromine with isotopes of mass 79 and 81, and an average atomic mass of 79.908.
Set up the equation: if x% is ⁷⁹Br, then % must be ⁸¹Br. So: 79x + 81 = 7990.8. Expanding this gives: 79x + 8100 - 81x = 7990.8, which simplifies to -2x = -109.2.
Solving gives x = 54.6, meaning ⁷⁹Br is 54.6% and ⁸¹Br is 45.4%. The key is setting up the algebra correctly and remembering that percentages must add up to 100.
Exam Hack: Always check your percentages add to 100% - it's an instant way to spot calculation errors!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Relative isotopic mass compares the mass of one specific isotope to 1/12th of a carbon-12 atom. Think of carbon-12 as the universal reference point - like using metres to measure length. Relative atomic mass is the weighted average of all isotopes of an element.
Relative formula mass (RFM) is simply the sum of all atomic masses in a compound. For NH₃, you add nitrogen (14) plus three hydrogens (1+1+1) to get 17. For more complex compounds like Al₂(SO₄)₃, count each atom carefully: 2 aluminium, 3 sulphur, and 12 oxygen atoms.
Hydrated compounds like CuSO₄·5H₂O include water molecules in the calculation. The dot means the water is loosely attached, but you still count all the atoms when calculating the RFM.
Memory Trick: Write out each atom individually when calculating RFM - it prevents you from missing atoms in brackets!
Access to all documents
Improve your grades
Join milions of students
By signing up you accept Terms of Service and Privacy Policy
Time of flight spectroscopy is the most common type of mass spectrometry you'll encounter. The entire apparatus operates under vacuum to prevent ions colliding with air molecules, which would mess up the results.
The process has three main stages: ionisation, acceleration, and ion drift. During ionisation, the sample dissolves in a volatile solvent and gets forced through a needle connected to high voltage. This creates tiny charged droplets that eventually become single positive ions.
All ions receive the same kinetic energy during acceleration, but heavier particles move slower than lighter ones. As ions travel down the flight tube, they separate based on their speed. The detector measures their arrival time and converts this into electrical signals.
Finally, a computer processes these signals to generate a mass spectrum - essentially a graph showing which masses are present and in what amounts. The whole system works because lighter ions reach the detector first.
Real-World Connection: Mass spectrometry is used everywhere from drug testing in sports to identifying explosives at airports!
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
You can download the app in the Google Play Store and in the 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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Dive into A-Level Chemistry with this comprehensive guide on mole calculations, including mole conversions, molar mass, and stoichiometry. This resource covers essential equations, practical examples, and detailed explanations to help you master the concepts of moles and their applications in gas volume and relative formula mass. Perfect for exam preparation and enhancing your understanding of quantitative chemistry.
ChemistryExplore the principles of mass spectrometry, including molecular fragmentation, mass spectra interpretation, and relative abundance analysis. This summary provides essential insights for AQA A-Level organic chemistry, helping students understand how to deduce molecular structures and identify compounds through mass spectrometry techniques.
ChemistryExplore essential calculations and concepts related to moles in chemistry. This summary covers molar mass, concentration, ideal gas equations, empirical and molecular formulas, and the significance of atom economy in chemical processes. Ideal for A-Level Chemistry students seeking to master the topic of 'Amount of Substance'.
ChemistryExplore the principles of mass spectrometry, including the calculation of relative atomic mass and the significance of isotopes. This summary covers key concepts such as isotopic mass, relative abundance, and the impact of vacuum conditions on ion behavior. Ideal for chemistry students preparing for exams.
ChemistryDive into the essentials of mole calculations, including empirical and molecular formulas, molar mass, and relative formula mass. This summary provides clear explanations and examples to help you master the concepts of chemical formulas and their calculations. Ideal for students preparing for exams or needing a quick reference.
ChemistryExplore key concepts in chemistry calculations, including relative atomic mass, moles, concentration, and molar mass. This summary provides essential formulas and methods for calculating percentage composition and average rates of reaction, tailored for students preparing for exams.
ChemistryApp 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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
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
I think it’s very much worth it and you’ll end up using it a lot once you get the hang of it and even after looking at others notes you can still ask your Artificial intelligence buddy the question and ask to simplify it if you still don’t get it!!! In the end I think it’s worth it 😊👍 ⚠️Also DID I MENTION ITS FREEE YOU DON’T HAVE TO PAY FOR ANYTHING AND STILL GET YOUR GRADES IN PERFECTLY❗️❗️⚠️
Thomas R
iOS user
Knowunity is the BEST app I’ve used in a minute. This is not an ai review or anything this is genuinely coming from a 7th grade student (I know 2011 im young) but dude this app is a 10/10 i have maintained a 3.8 gpa and have plenty of time for gaming. I love it and my mom is just happy I got good grades
Brad T
Android user
Not only did it help me find the answer but it also showed me alternative ways to solve it. I was horrible in math and science but now I have an a in both subjects. Thanks for the help🤍🤍
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
I found this app a couple years ago and it has only gotten better since then. I really love it because it can help with written questions and photo questions. Also, it can find study guides that other people have made as well as flashcard sets and practice tests. The free version is also amazing for students who might not be able to afford it. Would 100% recommend
Aubrey
iOS user
Best app if you're in Highschool or Junior high. I have been using this app for 2 school years and it's the best, it's good if you don't have anyone to help you with school work.😋🩷🎀
Marco B
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 app is phenomenal down to the correct info and the various topics you can study! I greatly recommend it for people who struggle with procrastination and those who need homework help. It has been perfectly accurate for world 1 history as far as I’ve seen! Geometry too!
Paul T
iOS user
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