[avigail landman]

Hi. I have a question:
say we take a certein matter, in constant pressude, so that it's volume can expand.
And we're aked- how much heat does it take to raise it's temp. by a certein degree.
So- we use :Qp= m*s*dt to calculate that.

Now- I'm asked, how much heat Q would I need to raise the temp. by the same degree, only in CONSTANT VOLUME, so that the pressure can change.

How do I put together the formulas for Qp and Qv?

Heat at const. pressure ---> Qp=dE+ PdV=dH
and so ---> dE=Qp-PdV

now: heat at const. volume ---> Qv=dE
so combining the 2 above I get: Qv=dE=Qp-PdV

Only I don't understand this: at const. volume I don't have dV, I have dP.

So- should I calculate the PdV and put in the formula , or the VdP?

Please *delete me* I can't get anyone to answer me! 

[gregdwulet]

Well, let's try an example.
Give us an example of a problem that you are trying to apply this to.