When the volume is kept constant, no work is done, so the amount of heat absorbed is completely used to raise the temperature of system. But when pressure is kept constant so work of expansion will be done. Thus, the amount of heat absorbed by system is not wholly used to raise the temperature but some part of heat is used to do some work of expansion. Thus when pressure is constant, more heat is to be given to system to raise its temperature by 1

^{o}C then when volume is kept constant.Thus, C

_{P}> C_{V}
The relation between C

_{P}and C_{V}can be calculated by finding difference between two so, we have
C

_{P}– C_{V}= dH/dT - dE/dT –––––––– (i).H = E + PV

and PV = nRT

\ H = E + nRT

For 1 mole of gas (molar heat is for 1 mole.)

H = E + RT –––––––––– (ii)

Differentiating (ii) w. r. to ‘T’, we get

dH/dT = dE/dT + R

Or dH/dT - dE/dT = R

Substituting in (i), we get

**C**

_{P}– C_{V}= R
I have a great fun reading your blogs. Thank you to the blogger. Have a great day.

ReplyDeletewww.imarksweb.org