The performance of an isothermal chemical engine with finite-rate mass
transfer and a mass leak is analysed in this paper. The relations bet
ween the optimal power output and the efficiency, the maximum power ou
tput and the corresponding efficiency and the maximum efficiency and t
he corresponding power output are derived on the ba!;is of linear (Ons
ager) mass-transfer law using the analogous method of finite-time ther
modynamics for a heat engine. There exists a maximum efficiency bound
with nonzero power output besides the maximum power output bound with
nonzero efficiency for the engine. This characteristic is different fr
om that for the chemical engine with the sole irreversibility of finit
e-rate mass transfer. The optimal region of parameter selection for th
e engine is provided and the effect of the mass-transfer law is analys
ed.