Reaction he/ore Complete Equilibrium. 485 



number of molecules of the solid CaC0 3 which have disappeared 

 in the same time. Therefore 



and from this follows : — 



, _ cc"2, T po—(c' + c±T)e'"^ T 'po ,.. . 



and 



,,/Cc'^tPo — (J + cSr)c"'Sr'j0 o '\-i 





i. e., the velocity of decomposition of solid CaC0 3 into solid. 

 CaO and C0 2 gets is at the time r a function of the surface of 

 the solid CaC0 3 , of the surface of the formed solid CaO, and 

 of the concentration of the C0 2 at the time r. 



If the evaporating surface of the solid CaC0 3 be kept con- 

 stant during the whole time of the reaction, we have 



/dt\ „ „, „/ K"-K'"2/ \ ,..,,. 



Let us now take another system : — 



n'A 1 gas or in sol. -f n n A n gas or in sol.^WBj gas or in sol. + m"B n gas 

 J-orf t or ^ [or in sol.. 



A n solid. B. x solid. 



e.^.K s C0 3 insol. + BaS0 4 in sol.^BaC0 3 in sol. + K 2 S0 4 in sol. 



j or | f or j 



BaSO* solid. BaC0 3 solid. 



At equilibrium the reactions BaS0 4 solid^or«-BaS0 4 in solution 

 and the reaction BaC0 3 solids or<-BaC0 3 in solution do not 

 take place ; only the reaction K 2 C0 3 in solution +BaS0 4 in 

 solution^ BaC0 3 in solution +K 2 S0 4 in solution is to be 

 considered. We have therefore 



^L —Jn > n ~^~ Jt n ni ) .iv_r ) 

 fo — C POP — tp o p — U, 



and since pj, p ,n are constant, we have 



p iT (concentration of S0 4 K 2 in solution) __,, 

 p' (concentration of C0 3 K 2 in solution) 



(Guldberg and Waage). 



