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# Help answering this a level question Watch

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1. For the last question the answer is 11.1 but I got 0.0111, can someone tell me how to work this out
2. (Original post by Lucofthewoods)
For the last question the answer is 11.1 but I got 0.0111, can someone tell me how to work this out
mulitply your answer by 1000 to give you volume in dm3, you have volume in m3, pay attention to the units they ask of you!
3. (Original post by thatawesomekid)
mulitply your answer by 1000 to give you volume in dm3, you have volume in m3, pay attention to the units they ask of you!
sorry this is a silly question but where does it say it's in m3? But thank you!
4. (Original post by Lucofthewoods)
For the last question the answer is 11.1 but I got 0.0111, can someone tell me how to work this out
The
ideal gas equation that you used will give an answer in m3. But the question asked for dm3 so you multiply your answer by 1000.
hope this helps
5. (Original post by DisturbedCustard)
The
ideal gas equation that you used will give an answer in m3. But the question asked for dm3 so you multiply your answer by 1000.
hope this helps
So unless told different do you assume it's the standard units?
6. (Original post by Lucofthewoods)
sorry this is a silly question but where does it say it's in m3? But thank you!
Question says to find volume in dm^3 on the second line.
The ideal gas equation (pV=nRT) will always give/ require volume to be in m^3 just as pressure must be in Pa, and temp in K. To convert the volume that you got (0.0111 m^3) to dm^3 you multiply by 1000. You've done the right working, just didn't finish it off by converting to the correct units
7. (Original post by Lucofthewoods)
So unless told different do you assume it's the standard units?
This has probably caused confusion because the ideal gas equation is used with two different sets of units.

With strict SI units you have volume in m3 and pressure in Nm-2 (Pa)

With the units often used in chemistry you have volume in dm3 and pressure in kPa.

You need to pay attention to the pressure given as this will give yo the volume units.

You should be thankful as a few years ago you could also have pressure in atm, which gives a different value for R (different units), or even pressure in mmHg (Torr).

At least now things are a little more standardised...

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