Can you average specific heat capacities when heating multiple substances together?

[Blissfulpain]

[SOLVED] Heat on Earth

just curious... would it be reasonable to add up all the materials in Earth and then average their specific heat capacities to determine an average amount of energy needed to warm the Earth by 1 degree?

i suppose it could be broken down to if you have 1 mol of liquid water and 1 mol of gaseous oxygen... and you try and heat both to 26 degrees celsius from 25 degrees celsius while they are mixed... can you average the specific heat capacities and then do the equation in one step.. or must you do the calculation for the energy required for water and oxygen separately?

i realize water and air don't mix.. but i still want to know if it holds true in a situation like that :) i suppose water and dissolved salt would make a better example... does the water's capacity get affected by being salinated?

 

[Nereid]

just curious... would it be reasonable to add up all the materials in Earth and then average their specific heat capacities to determine an average amount of energy needed to warm the Earth by 1 degree?

To some 0-th order, maybe; but how and where would you apply such a concept?

Consider, the core is much hotter than the surface, and it will take how long for the two to come to thermal equilibrium?

Also, there are rather too many phase changes that could happen in that 1 degree, so how do you make a sensible average to incorporate that?

Finally, how many chemical reactions will change over that one degree, and by how much?

 

[Blissfulpain]

good points there.. hmm.

never mind then... this gives me lots to think about thx