temperature
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temperature
Hi, this might be a dumb question but when doing calculations for thermodynamics, do we need to convert temperature to Kelvin from celsius?
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Re: temperature
Sometimes. if doing heat capacity calculations, only the change in temperature is important, and so you don't have to convert because the change will be the same in either system. However, when working with entropy. you should convert to Kelvin because the value of entropy depends upon the temperature in Kelvin.
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Re: temperature
I would say always look at the units that are in the question. If you are given a heat capacity in Kelvin, use Kelvin so that way your units cancel, and likewise for Celsius. In other words, just make all your units are consistent with each other and you should be good. Hope this helps!
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Re: temperature
I think it depends on the context of what you are being asked. For instance, if using heat capacity, then you may be able to keep the temperature units in Celsius as this is the unit given by heat capacity. Similarly, if you are asked to calculate entropy, it will probably be best to use Kelvin as other components of the equation you are using to solve this question are also in Kelvin. Just make sure to always be aware of what units are being given in the question and use appropriate units so they will cancel if need be!
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Re: temperature
As a rule of thumb, if you ever need to use an equation with the ideal gas constant R, you should definitely convert.
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Re: temperature
It depends on the question - I would pay attention to the units used.
For example, if you're dealing with specific heat capacity - those are in Celsius, so you would want the temperatures in your calculations to be in Celsius. However, if you are dealing with molar heat capacities - which are in Kelvin - you would want to use Kelvin temperatures instead. Additionally, in any of the work or entropy calculations, you want to use Kelvin as well, since the gas constant of 8.314 J/Kmol is in Kelvin.
For example, if you're dealing with specific heat capacity - those are in Celsius, so you would want the temperatures in your calculations to be in Celsius. However, if you are dealing with molar heat capacities - which are in Kelvin - you would want to use Kelvin temperatures instead. Additionally, in any of the work or entropy calculations, you want to use Kelvin as well, since the gas constant of 8.314 J/Kmol is in Kelvin.
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Re: temperature
If you are asked for the change in temperature you would not have the convert the units. In other cases, you should make sure your units for temperature are consistent with the constants you are multiplying it with.
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Re: temperature
Unless otherwise specified, I would probably go with Kelvin because the units tend to cancel out much more easily and works better with the ideal gas law
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Re: temperature
If changing the temperature I would say there is no need to convert units. If you use an equation with gas constant be sure to convert
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Re: temperature
It will depend on the problem in question and the units that are given. Sometimes, you can get away with keeping celcius if a change in temperature is needed (since the relative difference will be the same regardless of which unit). But other times call for Kelving to be used to do a difference in units.
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Re: temperature
Depending on the context of the problem you might have to convert a few things, including temperature. Just make sure you pay attention to the wording and context of a problem because it can be the difference between a right answer and a wrong answer!
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Re: temperature
I think a lot of the times you have to be wary of if the question gives the temperature in Celcius. Things utilizing the gas constant R, the second law of thermodynamics, etc. all have their units in Kelvin. In this case, you have to convert Celsius to Kelvin and make sure your units match up. However, when a change in temperature, delta T, needs to be calculated, no adjustments need to be made. Hope this helps!
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Re: temperature
I would say that it's good to convert to Kelvin whenever given a temperature in Celsius. Sometimes a question will ask for the final temperature in Celsius, but it's easy to convert back to it and when plugging in temperature into equations it's going to be in Kelvin, especially with ideal gas law.
Re: temperature
If it's concerning a change in temperature, then no. But most other cases, probably...
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Re: temperature
Agreeing with most comments, I think the context of the question matters. If the question mentions Kelvins then you should convert like when dealing with entropy. I think it is a good habit to just convert to Kelvin, even if it is not specifically stated because most questions seemed to be formatted that way.
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Re: temperature
Generally, I change everything to Kelvin because it is what is normally needed. However, in calculations where the change in temperature is important, it doesn't really matter which unit you use.
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Re: temperature
Usually, it is Kelvin that's most commonly used, but sometimes Celsius is needed for the answer.
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Re: temperature
Most of the time you need to convert temperature from celsius to kelvin. Especially when you using the gas constant you should make sure to do this. I always covert to SI units to be on the safer side. The only time when its acceptable not to change the units is when your calculating the change in T which has the same ratio either way.
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Re: temperature
If it's abt temp change then you don't really need to convert. Just pay attention to the units needed/what the question is asking for. Make sure you use the same temperature unit in calculations.
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Re: temperature
Definitely pay close attention to the context of the question. We usually use Kelvin, but there are times when Celsius is the correct unit to use.
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Re: temperature
It depends on the units used, for instance if you are using the gas constant with units J/Kmol it would be better to use temperature in Kelvins to let the units cancel out.
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Re: temperature
It really just depends on what formula you are using, as some have temperature in Kelvin while others have it in Celsius. Furthermore, always pay attention to your units, as they usually indicate if you ever need to convert between the two.
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Re: temperature
I think it just depends on what the question is asking for, but usually we'll use K.
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Re: temperature
Usually you'll need to convert to K because we need to make sure that our units cancel out (like with the gas constant), so double checking your units is always safest. Most calculations are in K because then temperature is always a positive value.
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Re: temperature
It can depend, so definitely check the problem to make sure your final answer is in the units that they are asking for. The conversion isn't too hard either, so sometimes it's better to be safe and use Kelvin since it's the SI unit.
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Re: temperature
This mostly depends on what units the question is asking for, but most of the time, convert to Kelvins.
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Re: temperature
For heat capacity questions you will usually use C but always double check with the specific heat of the problem (sometimes it can be different). For other applications though you will usually go from C to kelvin, especially in problems using ideal gas equations.
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Re: temperature
Most of the time yes, but it depends on the problem. Some problems give you items such as heat capacity in degrees celsius so you have to check before you assume kelvin.
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Re: temperature
I think depending on the type of question and which units are given, that is how to tell whether or not to convert from Celsius to Kelvin or vice versa.
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Re: temperature
I think to be safe, the only time you don't need to convert Celsius to Kelvin is when you are only looking at the change in temperature, but in other problems, I think just use Kelvin.
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Re: temperature
I would always look at the units of the rest of the terms you have in order to determine what temperature units to use. If you had to guess, I would probably go with Kelvin because that one seems to be more commonly used in calculations.
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Re: temperature
Yes! Be sure to add the amount of degrees Celsius to 273 to get your temperature in Kelvin
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Re: temperature
It depends on the context of the problem. Use whatever temperature scale that is relevant to the question. In general, when doing calculations for thermodynamics, Kelvin is usually used at a greater frequency than Celsius, but whichever one is applicable to the problem is the one you should use.
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