Chemical Thermodynamics and Energetics

W = -PΔV (For expansion)
W = PΔV (For compression)

$W_{max} = -2.303 nRT log_{10}{V_2}/{V_1}$

$W_{max} = -2.303 nRT log_{10}{P_1}/{P_2}$

ΔU = q + W

ΔH = ΔU + PΔV

ΔH = ΔU + ΔnRT

Hess’s Law: ΔH = Δ$H_1$ + Δ$H_2$ + Δ$H_3$

ΔS = ${q_{rev}}/{T} = {ΔH}/{T}$

ΔG = ΔH – TΔS

$ΔG^{o} = -2.303 RT log_{10}K$

(i)ΔG = 0, the system is at equilibrium

(ii)ΔG < 0, the system is spontaneous
(iii)ΔG > 0, the process is non-spontaneous

Δn = [No. of moles of gaseous products] – [No. of moles of gaseous reactants]

$q_p = ΔH$ and $q_v = ΔU$

$q_p = q_v = ΔnRT$

$ΔS_{total} = ΔS_{system} + ΔS_{surr}$

$ΔS_{surr} = -{ΔH}/{T}$

$\table \text"Nature of reactions",ΔH,ΔS,ΔG,\text"Spontaneity of reaction";Exothermic,-ve,-ve,\text"-ve at low T",\text"spontaneous at low temp.";Endothermic,+ve,+ve,\text"-ve at high T",\text"spontaneous only at high temperature";Exothermic,-ve,+ve,\text"-ve at all T",\text"spontaneous at all temperatures";Endothermic,+ve,-ve,\text"+ve at all T",\text"non-spontaneous at all temperatures"$