Chemistry calculations involving moles, concentrations, and gas volumes are essential...
Chemistry31 views·Updated 15 Jul 2026·2 pagesExploring Chapter 3.3: Quantities in Chemistry
1
of 2
Moles and Concentration
Concentration tells you exactly how much solute is packed into each cubic decimetre of solution - think of it like measuring how strong your squash is. The stronger the concentration, the more solute particles you've got floating about in there.
The key formula you need to master is c = n/v, where c is concentration (mol/dm³), n is moles, and v is volume (dm³). This simple equation lets you work out any of these three values if you know the other two.
Standard solutions are your reference points - solutions where you know the exact concentration. You'll make these using a volumetric flask, which gives you super-accurate measurements for your experiments.
Quick Tip: To convert between mol/dm³ and g/dm³, multiply or divide by the molar mass (M). This conversion pops up constantly in exam questions!
2
of 2
Gas Volume Calculations
Here's something brilliant about gases - equal volumes of different gases contain the same number of molecules at the same temperature and pressure. Whether it's oxygen, nitrogen, or carbon dioxide, they all follow this rule.
At room temperature and pressure (RTP), the molar gas volume is always 24.0 dm³/mol. This means one mole of any gas takes up exactly 24 dm³ of space. Use the formulas v(dm³) = n × 24 or v(cm³) = n × 24000 to work out gas volumes quickly.
For more complex situations, you'll need the ideal gas equation: pV = nRT. Remember your units here - pressure in pascals, volume in m³, temperature in Kelvin , and R = 8.314 J mol⁻¹K⁻¹.
Unit Watch: Always check your units! Convert kPa to Pa by multiplying by 1000, and don't forget to add 273 to Celsius temperatures.
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Chemistry31 views·Updated 15 Jul 2026·2 pagesExploring Chapter 3.3: Quantities in Chemistry
Chemistry calculations involving moles, concentrations, and gas volumes are essential skills you'll need for your A-levels. These formulas help you work out how much of a substance you have and how it behaves in solutions and as gases.
1
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Moles and Concentration
Concentration tells you exactly how much solute is packed into each cubic decimetre of solution - think of it like measuring how strong your squash is. The stronger the concentration, the more solute particles you've got floating about in there.
The key formula you need to master is c = n/v, where c is concentration (mol/dm³), n is moles, and v is volume (dm³). This simple equation lets you work out any of these three values if you know the other two.
Standard solutions are your reference points - solutions where you know the exact concentration. You'll make these using a volumetric flask, which gives you super-accurate measurements for your experiments.
Quick Tip: To convert between mol/dm³ and g/dm³, multiply or divide by the molar mass (M). This conversion pops up constantly in exam questions!
2
of 2Sign up to see the content. It's free!
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Gas Volume Calculations
Here's something brilliant about gases - equal volumes of different gases contain the same number of molecules at the same temperature and pressure. Whether it's oxygen, nitrogen, or carbon dioxide, they all follow this rule.
At room temperature and pressure (RTP), the molar gas volume is always 24.0 dm³/mol. This means one mole of any gas takes up exactly 24 dm³ of space. Use the formulas v(dm³) = n × 24 or v(cm³) = n × 24000 to work out gas volumes quickly.
For more complex situations, you'll need the ideal gas equation: pV = nRT. Remember your units here - pressure in pascals, volume in m³, temperature in Kelvin , and R = 8.314 J mol⁻¹K⁻¹.
Unit Watch: Always check your units! Convert kPa to Pa by multiplying by 1000, and don't forget to add 273 to Celsius temperatures.
We thought you’d never ask...
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.
You can download the app from Google Play Store and Apple App Store.
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Students love us — and so will you.
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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.
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