Units


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Tinisha 1G
Posts: 69
Joined: Fri Sep 28, 2018 12:17 am

Units

Postby Tinisha 1G » Wed Jan 09, 2019 8:31 pm

When we are calculating using the ideal gas law, should we put the temperature in Kelvins or in Celsius?

Samantha Man 1L
Posts: 63
Joined: Fri Sep 28, 2018 12:22 am

Re: Units

Postby Samantha Man 1L » Wed Jan 09, 2019 8:36 pm

When you're using PV=nRT, the temperature should always be in Kelvin units not Celsius.

megan blatt 2B
Posts: 61
Joined: Fri Sep 28, 2018 12:28 am

Re: Units

Postby megan blatt 2B » Wed Jan 09, 2019 9:11 pm

Yes, you would put temperature in Kelvin. Usually when doing calculations, Kelvin is the unit that should be used.

Margaret Akey
Posts: 80
Joined: Fri Sep 28, 2018 12:18 am

Re: Units

Postby Margaret Akey » Wed Jan 09, 2019 9:26 pm

always kelvin!

degrees celcius + 273.15 = kelvin

005199302
Posts: 108
Joined: Fri Sep 28, 2018 12:15 am

Re: Units

Postby 005199302 » Wed Jan 09, 2019 9:27 pm

We use Kelvin because as Dr. Lavelle mentioned in the beginning of 14A, Kelvin is an absolute scale (0 K is absolute zero).

Nicole Lee 4E
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am
Been upvoted: 1 time

Re: Units

Postby Nicole Lee 4E » Wed Jan 09, 2019 10:59 pm

The R constant's units are in Kelvin, so Kelvin should be used for temperature.

Kyither Min 2K
Posts: 60
Joined: Wed Oct 03, 2018 12:15 am

Re: Units

Postby Kyither Min 2K » Thu Jan 10, 2019 3:57 pm

The units should be in Kelvin as the universal gas constant, R is in Kelvin. To find convert from Celsius to Kelvin just add 273.15.

Hannah Yates 1K
Posts: 59
Joined: Fri Sep 28, 2018 12:27 am

Re: Units

Postby Hannah Yates 1K » Thu Jan 10, 2019 5:17 pm

Use Kelvin. In most equations with temperature, you always use Kelvin

LedaKnowles2E
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

Re: Units

Postby LedaKnowles2E » Thu Jan 10, 2019 5:22 pm

Since R is in Kelvin, use Kelvin. You almost always use Kelvin in chemistry.

LeannaPhan14BDis1D
Posts: 57
Joined: Fri Sep 28, 2018 12:16 am

Re: Units

Postby LeannaPhan14BDis1D » Fri Jan 11, 2019 3:16 pm

Lavelle said due to the absolute 0 K we use Kelvin like the other people said

Mhun-Jeong Isaac Lee 1B
Posts: 54
Joined: Fri Sep 28, 2018 12:17 am

Re: Units

Postby Mhun-Jeong Isaac Lee 1B » Fri Jan 11, 2019 5:37 pm

Yeah use K. Whenever you are confused as to which unit to use, look at the constant values in the equation and use the units that will cancel out with them. In this case of PV = nRT, R uses K.

Lopez_Melissa-Dis4E
Posts: 66
Joined: Fri Sep 28, 2018 12:20 am

Re: Units

Postby Lopez_Melissa-Dis4E » Fri Jan 11, 2019 5:50 pm

Kelvin should be used when calculating these type of problems due to the fact that 0 Kelvin is absolute 0.

riddhiduggal
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

Re: Units

Postby riddhiduggal » Fri Jan 11, 2019 6:11 pm

You should always convert temperatures to Kelvin in PV=nRT

JadeSebti1L
Posts: 35
Joined: Fri Sep 28, 2018 12:19 am

Re: Units

Postby JadeSebti1L » Fri Jan 11, 2019 6:16 pm

Yes, as people said before you should always use Kelvin. It is also important to note that you must match pressure units for whatever R constant you are using or else your answer will be incorrect. You can also convert to whatever units the question asks before plugging in your values to PV=nRT.

Mariana Fuentes 4l
Posts: 21
Joined: Wed Nov 15, 2017 3:00 am

Re: Units

Postby Mariana Fuentes 4l » Sun Jan 13, 2019 1:57 pm

You use Kelvin since R is in terms of Kelvin. If you were given a different temperature unit, you would have to convert it to Kelvin.

Example, 52 degrees Celsius to K.
C+273.15=K
52+273.15=300.15K

Arta Kasaeian 2C
Posts: 30
Joined: Mon Jan 07, 2019 8:22 am

Re: Units

Postby Arta Kasaeian 2C » Sun Jan 13, 2019 2:41 pm

The temperature is always plugged in as Kelvin. If the question concern the change in temperature in celsius, you calculate using kelvins and convert to celsius in the last step.

PranitKumaran1F
Posts: 30
Joined: Thu Nov 08, 2018 12:17 am

Re: Units

Postby PranitKumaran1F » Sun Jan 13, 2019 2:47 pm

The units should be in kelvin using the ideal gas law equation

404982241
Posts: 47
Joined: Fri Sep 28, 2018 12:17 am

Re: Units

Postby 404982241 » Sun Jan 13, 2019 8:50 pm

always use kelvins. add 273.15 to Celsius to get kelvins. remember to make sure that the temperature remains the same during the reaction/s.

Brian Chang 2H
Posts: 65
Joined: Fri Sep 28, 2018 12:17 am

Re: Units

Postby Brian Chang 2H » Sun Jan 13, 2019 10:38 pm

Use Kelvin.

The Gas Constant is in Kelvin so we have to use the same measurement for temperature.

To get Kelvin, just add 273.15 to your Celcius measurement.

Millicent Navarro 1I
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am

Re: Units

Postby Millicent Navarro 1I » Mon Jan 14, 2019 2:46 pm

Always use Kelvin! If a problem states a temperature in Celsius (this is very common) or Fahrenheit, convert it to Kelvin.


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