You are Here: Home

1. Do I need specific units for P, and V for these laws?
P1V1/T1=P2V2/T2 or PV=nRT
I know it's a bit silly but I forgot and I'm not quite sure but I know T is in Kelvin.

Posted from TSR Mobile
2. (Original post by Expialidocious)
Do I need specific units for P, and V for these laws?
P1V1/T1=P2V2/T2 or PV=nRT
I know it's a bit silly but I forgot and I'm not quite sure but I know T is in Kelvin.

Posted from TSR Mobile
Well usually you'd use SI units i.e. Pa and m3

For the equations above, i'd advise using the units ; P -> Pa
V -> m3
T -> K
n -> mol
3. But is it essential to convert like atm to Pa? Or is it alright if I'd use atm for the combined law?

Posted from TSR Mobile
4. (Original post by ZakRob)
Well usually you'd use SI units i.e. Pa and Dm

For the equations above, i'd advise using the units ; P -> Pa V -> Dm-3 T -> K n -> mol
Decimetres are not SI units. Metres are. Units of volume are m3
(Original post by Expialidocious)
But is it essential to convert like atm to Pa? Or is it alright if I'd use atm for the combined law?
Posted from TSR Mobile
It is unfortunately essential 1atm =100,000 Pa
5. (Original post by joostan)
Decimetres are not SI units. Metres are. Units of volume are m3

It is unfortunately essential 1atm =100,000 Pa
Yeah that's what I meant m3 for volume, I don't why I put dm-3. I've changed it now anyway.
6. (Original post by ZakRob)
Yeah that's what I meant m3 for volume, I don't why I put dm-3. I've changed it now anyway.
Concentration's the funny one for chem. No worries
7. I feel quite stupid for asking this again but for Boyle's and Charles' Law, I'd need to convert it to STP right? I'm so so sorry

Posted from TSR Mobile
8. (Original post by Expialidocious)
I feel quite stupid for asking this again but for Boyle's and Charles' Law, I'd need to convert it to STP right? I'm so so sorry

Posted from TSR Mobile
No it does not need to be STP. Converting to STP is impossible without changing the reaction. STP is standard temperature and pressure. You do however need SI units again
9. (Original post by joostan)
Decimetres are not SI units. Metres are. Units of volume are m3

It is unfortunately essential 1atm =100,000 Pa
1 atmospheric pressure is just slightly higher than 1 bar = 10^5 Pa.
10. (Original post by shengoc)
1 atmospheric pressure is just slightly higher than 1 bar = 10^5 Pa.
Yeah, but 101325 is so much messier
11. (Original post by joostan)
Yeah, but 101325 is so much messier
you are fortunate i am not a mathematician to argue the "power" of the equal sign. LOL
12. (Original post by shengoc)
you are fortunate i am not a mathematician to argue the "power" of the equal sign. LOL
say wha?
13. For the combined gas law you need pressure in Pa, temperature in K, volume in m3. For the ideal gas law, you can use whatever units you like - so long as your R compensates!

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 11, 2013
Today on TSR

### Edexcel C3 Maths Unofficial Markscheme

Find out how you've done here

### 1,041

students online now

Exam discussions

### Find your exam discussion here

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE