Homework Help: Difficult thermodynamics question (p. chem)

ok, here's a tricky brainteaser, whoever solves it is incredibly smart

uhh, actually, it's homework, and it seems pretty basic. Well, here it goes

"explain how liquid water can go from 25C/1 atm to 30C/1 atm in a process for which q<0"

I was thinking perhaps that since [tex]q=mc_p \Delta T [/tex], how can q be negative when the temperature change is positive? , maybe it's due to the specific heat, however the only other factor which effects cp is temperature right? Well since the tempreature change is already given, I'm not quite sure how one can say that it is due to cp, me thinks it shouldn't be.

I guess it has to do with internal energy, but how is it that q is not always dependent on temperature then when we are given the q equation? How can we explain the situation in terms of the heat equation (above).

 

yeah i wasnt getting any answer so, i posted in the engineering forum also

so i guess it has to be due to cp then since

[tex] q_p= \int C_p(T) dT [/tex]

and the overall temperature change is positive, right? i need a mathematical validation.

 

i see what you mean, well in the engineering forum they suggested that the temperature could be raised by doing work on the system, this makes sense. That's probably the answer. thanks for your help, you are definitely right in that it may or not be reversible path, also i learned that cp or cv can not be negative.