Gas Volume Gauntlet
The molar volume of a gas: one mole of any gas fills 24 dm3 at room temperature and pressure, so you multiply moles by 24 to find a volume, divide by 24 to find moles, and convert between cm3 and dm3 by 1000.
Get the method right under pressure
Free interactive practice on the steps that lose marks under exam pressure.
Start revising freeWhat you'll cover
One number unlocks every gas
At room temperature and pressure, one mole of any gas takes up the same space: 24 dm3. That single figure lets you turn moles into a volume or a volume back into moles, whatever the gas is. This module drills that conversion and the unit change between cm3 and dm3 that trips up so many answers.
Gas words to know
Learn these before you take on the calculations.
Which way are you going?
The same figure works in both directions; only the operation changes.
State the figure, then step through
In the exam, write 24 dm3 for one mole of gas before you touch the numbers. Going from moles, multiply by that figure; going the other way, divide by it. Then guard the units: a volume in cm3 must be made smaller into dm3 by 1000 before you use the figure, and a dm3 answer becomes cm3 by 1000 the other way. State the value and show each step.
Match the term
- molar volume
- 24 dm3 per mole
- multiply by 24
- divide by 24
- the space one mole of any gas fills at RTP
- the value of that space at RTP
- how to turn moles into a gas volume
- how to turn a gas volume into moles
Match the working
- 2 moles of gas at RTP
- 72 dm3 of gas at RTP
- 3000 cm3
- 5 dm3
- takes up 48 dm3
- is 3 moles
- is the same as 3 dm3
- is the same as 5000 cm3
How big is one mole?
How many dm3 does one mole of any gas occupy at room temperature and pressure?
- 24 dm3
- 12 dm3
- 48 dm3
- 1000 dm3
True about gas volumes
Select the TWO true statements about gas volumes at RTP.
- One mole of any gas takes up 24 dm3 at RTP
- To find a gas volume you multiply the moles by 24
- To change cm3 into dm3 you multiply by 1000
- Heavier gases take up more volume per mole
Work out the volume
A reaction makes 3 moles of carbon dioxide gas at room temperature and pressure. Multiply the number of moles by 24 to find the volume in dm3. What is the answer?
Order the working
Put the steps of finding a gas volume from moles in order, earliest first.
- Write down 24 dm3 for one mole
- Take the number of moles
- Multiply the moles by 24
- Read off the volume in dm3
Complete the rules
At room temperature and pressure, one mole of any gas takes up _____ dm3. To find a volume you _____ the moles by this figure. To find the moles you _____ the volume by it. To change a volume from cm3 into dm3 you divide by _____.
Spot the correct statements
Tap the TWO statements that are correct about molar volume.
- one mole of any gas fills 24 dm3 at RTP
- to get moles, divide the gas volume by 24
- one mole of gas fills only 24 cm3 at RTP
- heavier gases fill more space for each mole
Choose the step
Read each task and choose the correct step.
- You know the number of moles of a gas and want its volume in dm3. What do you do?
- You have a gas volume in dm3 and want the number of moles. What do you do?
- A gas volume is given in cm3, but you need it in dm3 before using the 24 figure. What do you do first?
Explain the gas calculation
Explain how to work out the volume of a gas from the number of moles, and how to convert between cm3 and dm3.
- State the volume that one mole of any gas takes up at RTP
- Explain how to find a volume from moles and moles from a volume
- Explain how to convert cm3 into dm3 and back again