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Chemistry83 views·Updated May 31, 2026·2 pagesMass Calculations Using Balanced Chemical Equations
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Calculating Mass from Balanced Equations - Magnesium Example
When magnesium reacts with sulphuric acid, you can calculate exactly how much hydrogen gas will be produced. The key is following a systematic approach that breaks down the problem into manageable steps.
Start with your balanced equation: Mg + H₂SO₄ → MgSO₄ + H₂. Always check the equation is balanced first - this one already is! Next, identify what you're given (0.2g of magnesium) and what you need to find (mass of hydrogen).
Calculate the moles of magnesium using n = m/GFM. With magnesium's GFM being 24.5, you get n = 0.2/24.5 = 0.008163 mol. The mole ratio from the equation shows 1:1 between Mg and H₂, so you'll also get 0.008163 mol of hydrogen.
Finally, convert moles of hydrogen back to mass using m = n × GFM. With hydrogen's GFM of 2, the answer is 0.008163 × 2 = 0.016g of hydrogen. This step-by-step method works for any similar calculation!
Remember: The mole ratio from your balanced equation is the bridge between reactants and products - it's absolutely crucial for getting the right answer.
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of 2
Iron Oxide Reduction Calculation
Reducing iron oxide with carbon monoxide is a classic industrial process, and you can calculate the iron yield using the same systematic approach. The balanced equation Fe₂O₃ + 3CO → 3CO + 2Fe shows the stoichiometric relationships you need.
Starting with 6.4g of iron(III) oxide, calculate its moles first. The GFM of Fe₂O₃ is (56×2) + (16×3) = 160, giving you n = 6.4/160 = 0.04 mol of iron oxide.
The mole ratio is crucial here - notice that 1 mole of Fe₂O₃ produces 2 moles of Fe. So 0.04 mol of iron oxide will produce 0.04 × 2 = 0.08 mol of iron. This 1:2 ratio comes directly from the balanced equation.
Convert the moles of iron to mass using iron's GFM of 56: m = 0.08 × 56 = 4.48g of iron. Notice how the mole ratio determines your final answer - getting this step right is essential for exam success.
Top Tip: Always double-check your mole ratios from the balanced equation - they're often where students make mistakes in calculations.
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Chemistry83 views·Updated May 31, 2026·2 pagesMass Calculations Using Balanced Chemical Equations
S
SJ @sj_hkza
Ever wondered how chemists work out exactly how much product they'll get from a reaction? These calculations help you predict quantities in chemical reactions using balanced equations - a crucial skill for your chemistry exams and practical work.
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Calculating Mass from Balanced Equations - Magnesium Example
When magnesium reacts with sulphuric acid, you can calculate exactly how much hydrogen gas will be produced. The key is following a systematic approach that breaks down the problem into manageable steps.
Start with your balanced equation: Mg + H₂SO₄ → MgSO₄ + H₂. Always check the equation is balanced first - this one already is! Next, identify what you're given (0.2g of magnesium) and what you need to find (mass of hydrogen).
Calculate the moles of magnesium using n = m/GFM. With magnesium's GFM being 24.5, you get n = 0.2/24.5 = 0.008163 mol. The mole ratio from the equation shows 1:1 between Mg and H₂, so you'll also get 0.008163 mol of hydrogen.
Finally, convert moles of hydrogen back to mass using m = n × GFM. With hydrogen's GFM of 2, the answer is 0.008163 × 2 = 0.016g of hydrogen. This step-by-step method works for any similar calculation!
Remember: The mole ratio from your balanced equation is the bridge between reactants and products - it's absolutely crucial for getting the right answer.
2
of 2Sign up to see the content. It's free!
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Iron Oxide Reduction Calculation
Reducing iron oxide with carbon monoxide is a classic industrial process, and you can calculate the iron yield using the same systematic approach. The balanced equation Fe₂O₃ + 3CO → 3CO + 2Fe shows the stoichiometric relationships you need.
Starting with 6.4g of iron(III) oxide, calculate its moles first. The GFM of Fe₂O₃ is (56×2) + (16×3) = 160, giving you n = 6.4/160 = 0.04 mol of iron oxide.
The mole ratio is crucial here - notice that 1 mole of Fe₂O₃ produces 2 moles of Fe. So 0.04 mol of iron oxide will produce 0.04 × 2 = 0.08 mol of iron. This 1:2 ratio comes directly from the balanced equation.
Convert the moles of iron to mass using iron's GFM of 56: m = 0.08 × 56 = 4.48g of iron. Notice how the mole ratio determines your final answer - getting this step right is essential for exam success.
Top Tip: Always double-check your mole ratios from the balanced equation - they're often where students make mistakes in calculations.
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.
Similar content
Most popular content: Stoichiometry
2Most popular content in Chemistry
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google 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 SiOS 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 KlichAndroid 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.
AnnaiOS user