Units of Temperature
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Units of Temperature
When using the ideal gas law, which units should the temperature be in? Kelvins or Celsius?
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Re: Units of Temperature
Juwan_Madaki_3K wrote:When using the ideal gas law, which units should the temperature be in? Kelvins or Celsius?
Kelvin
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Re: Units of Temperature
From what I have seen usually questions will provide us with the temperature in Celsius and we are expected to covert it to Kelvin.
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Re: Units of Temperature
Since the gas constant R typically has temperature units in Kelvin (and we want the temperature units to cancel out when solving for P,V or n), we list the temperature in Kelvin.
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Re: Units of Temperature
When converting between Celsius and Kelvin, you have to add or subtract how many degrees to Celsius to convert it into Kelvin again? And when converting from Fahrenheit, would it be easier to convert it into celsius first?
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Re: Units of Temperature
John Calonia 1D wrote:When converting between Celsius and Kelvin, you have to add or subtract how many degrees to Celsius to convert it into Kelvin again? And when converting from Fahrenheit, would it be easier to convert it into celsius first?
to convert Celsius to Kelvin, you add 273.15 to the temperature. I don't think we'll see any questions that expect us to convert Fahrenheit.
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Re: Units of Temperature
You would want it to be in Kelvin since the constant R has Kelvins and you want the units to cancel.
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Re: Units of Temperature
You would use Kelvin. Often times the temperature is given in Celsius, so you would have to add 273.15 to convert it to Kelvin.
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Re: Units of Temperature
For the Ideal Gas Law, you would use Kelvin. If you get a question where it gives you temperature in Celsius, all you have to do is add 273.15 in order to convert it to Kelvin.
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Re: Units of Temperature
I'm pretty sure we will be using Kelvin. So it will be important to know how to convert to Kelvin if not given Kelvin
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Re: Units of Temperature
When working with the ideal gas laws we would use Kelvin as our unit for temperature.
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Re: Units of Temperature
if you ever forget, you can just look at the units of the ideal gas constant, which always has K in the denominator.
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Re: Units of Temperature
According to the lecture, we should use Kelvin so that the units cancel out properly.
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Re: Units of Temperature
We have to use Kelvin, but we will have the conversion equation on the equation sheet I believe in case we are given celsius.
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Re: Units of Temperature
This one is actually important, we use Kelvin for the temperature in the Ideal Gas Equation.
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Re: Units of Temperature
We always use Kelvin for temperature in PV=nRT. This is simply because the units cancel out with the units of the other species in the equation.
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Re: Units of Temperature
You will always be using Kelvin since when looking at the other units in PV=nRT, there is only kelvin being used, so if using celsius for example, the units will not cancel out. Hope this helps!
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Re: Units of Temperature
So when using PV=NRT temperature is supposed to be inputted in Kelvin? How come though fro most of the questions so far we are being given temperature in Celcius?
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Re: Units of Temperature
Javier Perez M 1H wrote:So when using PV=NRT temperature is supposed to be inputted in Kelvin? How come though fro most of the questions so far we are being given temperature in Celcius?
I have noticed this as well...maybe it's just good conversion practice.
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Re: Units of Temperature
Kelvin should be used. If the temperature is given in Celsius, a simple conversion to Kelvin will be enough for you to use the PV=NRT equation correctly.
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Re: Units of Temperature
You should use Kelvin for the Ideal Gas Law and other temperature equations.
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Re: Units of Temperature
I believe he mentioned in lecture that it should be in Kelvin, and most likely we should know how to covert from celsius if the problem gives us temperature in that unit.
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Re: Units of Temperature
For the ideal gas law, the temperature should be in Kelvin. In order for gas laws to work, temperature has to be calculated on an absolute scale (Kelvin) rather than an arbitrary scale (Celsius). 0 K is absolute zero, but 0 C is just the melting point of water.
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Re: Units of Temperature
This should always be in kelvin, and I think the kelvin/celsius conversion formula is on our formula sheet, in case its needed on an exam.
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Re: Units of Temperature
We would need to write the temperature in Kelvin, therefore when we are given the temperature in Celsius we would have to convert it to Kelvin by adding 273.15 to the temperature.
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Re: Units of Temperature
We usually use Kelvin when calculating temperature. There is a formula to change Degrees to Kelvin; T(K)=T(C) + 273.15
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Re: Units of Temperature
Kelvin is used because it has a bigger and more applicable range for the chemicals we are experimenting with
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Re: Units of Temperature
Hi! Since the standard unit of temperature is Kelvin, your answer should always be in Kelvin.
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Re: Units of Temperature
Juwan_Madaki_3K wrote:When using the ideal gas law, which units should the temperature be in? Kelvins or Celsius?
I believe most of the time in 14B we will be using Kelvin for temperature unless a specific problem indicates otherwise!
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Re: Units of Temperature
Kelvins are always used. You can convert Celsius to Kelvin by adding 273.15
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Re: Units of Temperature
Kelvin is the correct unit to use. Using dimensional analysis, you will see that the units of Kelvin cancel out in calculations with ideal gas law! If provided Celsius, you can calculate the temperature in Kelvin by adding 273.15 to this value!
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Re: Units of Temperature
When you are prompted an ideal gas law, you would expres the temperature in Kelvin. If you are prompted the temperature in units of Celsius you would just convert to Kelvin.
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Re: Units of Temperature
For the ideal gas law you want to use Kelvins because it often cancels with the R.
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Re: Units of Temperature
You would use Kelvins. Converting Celsius to Kelvin is simple. All you have to do is add the degrees in Celsius to 273.15.
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Re: Units of Temperature
We would use Kelvin when using units of temperature in an equilibrium problem. The temperature of the reaction directly affects the products of the reaction and it is crucial that the units are correct to get our correct answer for our equilibrium constant.
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Re: Units of Temperature
When we work with temperature, you'll often times have to convert Celsius to Kelvin units, since Kelvin gives a more accurate description of the speed in which molecules move.
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Re: Units of Temperature
Juwan_Madaki_3K wrote:When using the ideal gas law, which units should the temperature be in? Kelvins or Celsius?
You would use Kelvin for the ideal gas law
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Re: Units of Temperature
Juwan_Madaki_3K wrote:When using the ideal gas law, which units should the temperature be in? Kelvins or Celsius?
The temperature should be in Kelvin.
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Re: Units of Temperature
0 Kelvin, which is -273.15° on the Celsius scale, is absolute zero. While the Celcius scale is calibrated in terms of the freezing and boiling points of water, the Kelvin scale is calibrated in terms of energy itself. At absolute zero, the substance has no kinetic energy - the lowest possible temperature. Thus, there are no negative numbers on the Kelvin scale to affect calculations and that is why we use it as the SI unit of temperature.
Converting degrees Celcius to Kelvin is relatively simple though so you shouldn't worry too much about that. You just add 273.15 degrees to whatever the Celcius temperature is to get Kelvin. Fahrenheit, on the other hand, is the conversion you should memorize.
Image credit: Wikihow Staff - How to Convert Fahrenheit to Kelvin, 2019
Converting degrees Celcius to Kelvin is relatively simple though so you shouldn't worry too much about that. You just add 273.15 degrees to whatever the Celcius temperature is to get Kelvin. Fahrenheit, on the other hand, is the conversion you should memorize.
Image credit: Wikihow Staff - How to Convert Fahrenheit to Kelvin, 2019
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Re: Units of Temperature
You should always work in Kelvin for calcualtion in Chemistry. Do not use Celsius. For the ideal gas law,
P: pressure [atm]
V: volume [Liters]
n: moles [mol]
R: constant [kg⋅m^2·K^−1⋅mol^−1s^−2], although these units are not as important, if you put the other variables in the correct units - it should cancel
T: temperature [Kelvin]
P: pressure [atm]
V: volume [Liters]
n: moles [mol]
R: constant [kg⋅m^2·K^−1⋅mol^−1s^−2], although these units are not as important, if you put the other variables in the correct units - it should cancel
T: temperature [Kelvin]
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Re: Units of Temperature
Concerning Kc or Kp we will use Kelvin, but we have not gone into detail about when or how to calculate the temperature.
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Re: Units of Temperature
We should use Kelvin for all of chemistry. Many temperatures will be given in Celsius, so to convert from Celsius to Kelvin, you add 273 to the Celsius temperature.
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Re: Units of Temperature
Hi! Kelvin should be used, and I think the conversion is on the equations sheet, but it's also fairly simple so attempting to remember to add 273.15 (in order to convert Celsius to Kelvin) would probably be a good idea.
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