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atm vs. bar?

Posted: Wed Jan 23, 2019 10:33 am
by Tyra Nguyen 4H
What's the difference between atm and bar when calculating the equilibrium constant with pressure?

Re: atm vs. bar?

Posted: Wed Jan 23, 2019 11:16 am
by Tarika Gujral 1K
Different units of measurement
Thus entails use of different value for R constant.

Re: atm vs. bar?

Posted: Wed Jan 23, 2019 11:19 am
by Shally Li 2C
Bar is the standard unit of pressure but 1 atm is equal to approximately 1.01 bar so when calculating equilibrium constant they are about the same.

Re: atm vs. bar?

Posted: Wed Jan 23, 2019 11:30 am
by Simran Rai 4E
Regarding pressure, they're both just units measurements. But if you wanted to figure out concentration you would need to use atm.
For example, if you're given partial pressure but the units are in bar and you want to use PV=nRT to find concentration (with volume given), you'd need to convert to atm because those are the units used in the R constant and therefore those would allow you to cancel out.

Re: atm vs. bar?

Posted: Sat Jan 26, 2019 12:33 pm
by vaishali 1D
They're different units of measure for pressure. It's essential that you identify the correct units in order to plug in the correct value for the R constant in PV=nRT.

Re: atm vs. bar?

Posted: Sat Jan 26, 2019 11:29 pm
by Eruchi Okpara 2E
There is a difference in the conversion formula that is used for both. I think its a difference in the R constant that is used for the formula PV=nRT.

Re: atm vs. bar?

Posted: Sun Jan 27, 2019 1:18 pm
by Alexandra Albers 1D
atm and bar are both units of measurements for the partial pressures of gases. If you have a problem where you need to find the equilibrium constant in partial pressures then you can leave the gases in either atm or bar (whichever they are given in). The only time that the difference becomes relevant in the problem is if you need the gases in concentrations and not partial pressures because you will need to change the value of R (the gas constant) depending on which unit you are in.

Re: atm vs. bar?

Posted: Sun Jan 27, 2019 1:45 pm
by Bruce Chen 2H
I believe that in the calculations that we are doing, we should use the unit that they give us... otherwise, I think they are interchangeable.

Re: atm vs. bar?

Posted: Wed Jan 30, 2019 10:20 pm
by Karina Jiayu Xu 4E
On the test I used bar and it was fine

Re: atm vs. bar?

Posted: Thu Jan 31, 2019 2:20 pm
by isarose0
bar is slightly more accurate than atm, by one percent

Re: atm vs. bar?

Posted: Thu Jan 31, 2019 2:39 pm
by shaunajava2e
they are both units of measurement for pressure and depending on your TA, both should be fine to use

Re: atm vs. bar?

Posted: Thu Jan 31, 2019 3:39 pm
by Millicent Navarro 1I
Both atm and bar are units of partial pressures of gases! However, it's important you stick to just one or the other when calculating equilibrium constant with pressure.

Re: atm vs. bar?

Posted: Thu Jan 31, 2019 4:02 pm
by Dayna Pham 1I
Karina Jiayu Xu 4E wrote:On the test I used bar and it was fine


My TA said she would’ve accepted both atm and bar on the test, but I’ve also heard that atm is more standard.

Re: atm vs. bar?

Posted: Sun Feb 03, 2019 2:32 pm
by Amar Singh
Practically you can usually use both but you should definitely use whichever one is specified in the problem.

Re: atm vs. bar?

Posted: Sun Feb 03, 2019 3:10 pm
by Edward Suarez 1I
i had the same question but I realized that most of the problems that had bar in the question had the answer in bar too

Re: atm vs. bar?

Posted: Wed Feb 06, 2019 1:22 pm
by Esther Lee 4H
im not sure if there's like a rule for it but it seems like we've been using bar way more than atm. they're both measuring pressure so I dont think there's a specific one you need to use but someone correct me if I'm wrong please

Re: atm vs. bar?

Posted: Fri Feb 08, 2019 4:56 pm
by Brian Kwak 1D
I think the most important part for atm and bar is to be consistent with the units throughout the calculations so you don’t get points deducted. I would really pay attention to the wording of the problem if they give you atm then just use atm throughout your calculations. Consistency is important, that’s what I think also either atm or bar is acceptable from what I was told by my TA. The choice is really dependent on the information they give you and the units in the given information.

Re: atm vs. bar?

Posted: Sun Feb 10, 2019 10:27 pm
by Anna O 2C
They simply correspond with different values, but distinguishing between them is essential in order to use the correct R constant value.

Re: atm vs. bar?

Posted: Wed Feb 20, 2019 3:12 am
by Xingzheng Sun 2K
So which one is the right unit for the equation PV=nRT?

Re: atm vs. bar?

Posted: Wed Feb 20, 2019 10:42 pm
by Jeannine 1I
Xingzheng Sun 2K wrote:So which one is the right unit for the equation PV=nRT?

I'd say it depends on which unit the problem uses. Can anyone confirm this?

Re: atm vs. bar?

Posted: Tue Feb 26, 2019 11:19 pm
by Lauren Huang 1H
The units can be atm or bar depending on the problem. Note that this will change the value of R.

Re: atm vs. bar?

Posted: Fri Mar 15, 2019 1:22 pm
by Shibhon_Shepard
when calculating for R just use the 8.314 value

Re: atm vs. bar?

Posted: Fri Mar 15, 2019 9:33 pm
by Nghi Nguyen 2L
there isn't that much of a difference between them , just use the unit that the problem states and make sure your R value corresponds

Re: atm vs. bar?

Posted: Sat Mar 16, 2019 12:44 pm
by jocelyntzeng
you can easily convert between the two but just be careful to use the right R value corresponding