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Constant pressure in a calorimeter

Posted: Tue Feb 11, 2020 1:22 pm
by Jielena_Bragasin2G
Since pressure is always constant in a calorimeter, are all reactions in a calorimeter constant?

Re: Constant pressure in a calorimeter

Posted: Tue Feb 11, 2020 5:37 pm
by jisulee1C
In a reaction there are variables that change. If the pressure is constant, the temperature or volume or number of moles or other things could be changing. In fact if the pressure is constant it would be an isobaric process where heat could be used to both do work and change the internal energy of the system.

Re: Constant pressure in a calorimeter

Posted: Wed Feb 12, 2020 9:03 pm
by Miriam Villarreal 1J
A constant-pressure calorimeter measures the change in enthalpy of a reaction occurring in a liquid solution. In that case, the gaseous pressure above the solution remains constant, and we say that the reaction is occurring under conditions of constant pressure.

Re: Constant pressure in a calorimeter

Posted: Wed Feb 12, 2020 9:56 pm
by Tiffany_Chen 2K
Adding on, for a regular calorimeter, it is constant pressure (air can diffuse in and out). Bomb calorimeter, it is constant volume as it's a sealed container, thus you would use Cv.