Question

How do you calculate the final temperature of the products of a chemical reaction assuming the process is adiabatic?

Answer 1

TO calculate the final temperature of the products of a chemical reaction assuming the process is adiabatic

we must know that for an adiabatic process q = 0 (means no heat is allowed or escaped from system )

as  q = 0

the expression U= q + W becomes

(U =  W or    U = - P dv ......(1)

C_v ( heat capacity at constant volume ) = d q (at costant volume ) / dt = dU /dt at constant volume

dU = C_v dt

putting this vaue of dU in equation no (1) we get

C_vdt = -Pdv or we know that

    H = (U + PdV)   = U + (PV) = U + (RT) = U + RT

= (C_v+R) T =  (C_v+R) (T₂-T₁) = C_p  (T₂-T₁)

thus by knowing value of Cp heat capacity at constant pressure ,  H , initial temperature final temperature for the reaction can be easily calculated .