PHYSICAL CHEMISTRY IN BRIEF

CHAP. 4: APPLICATION OF THERMODYNAMICS [CONTENTS] 117

(^12)

4 3

a

b

c

d

Sm

T

Obr.4.2:The Carnot cycle in variablesT−Sm. The line segmentsaandcrunning parallel to the
axisSmare the isotherms [T 2 ] and [T 1 ]. The line segmentsbanddrunning parallel to the axisT are
adiabats (all processes in the Carnot cycle are reversible, the reversible adiabats are isentropic lines).

Note:The inequality (4.31) has nothing to do with mechanical losses (e.g. by friction). It

is based on the fact that irreversible work is smaller than reversible work.

Example

The Carnot heat engine received heatQ 2 = 100 J from a heat reservoir of temperatureT 2 =

600 K, performed work, delivered heat−Q 1 to the cooler reservoir of temperatureT 1 = 300 K,

and returned to the initial state. Calculate the engine’s efficiency, the performed work and the

supplied heat.