∆E= ∆H– RT∆n= ∆H– P∆V= q + w
∆H= ∆E + ∆(PV) = q – w + P∆V
w= −P∆V= −nRTlnV
V
i
f
Done on a system Done by a system
Work, w +w −w
Heat, q +q(endothermic) −q(exothermic)
- “bomb” calorimeter
∆E= qv(valid with constant volume: “bomb” calorimeter)
qreaction= −(qwater+ qbomb)
qbomb = C ⋅∆t
where C= calorimeter constant (heat capacity) in J/°C.
- “coffee cup” calorimeter
∆H= qp(valid with constant pressure: “coffee cup” calorimeter)
q = m⋅c ⋅∆t
t
Cp H
∆
=∆
H H
products
reactants
reaction path
Exothermic
(heat released)
H H −
products
reactants
reaction path
Endothermic
(heat absorbed)
+
Part II: Specific Topics