Stability of naphthalene picrate from

To determine the free energ of formation from its solid components ot the addition compound of napthalene and picric acid by measurement of e.m.f. 

Naphthalene and picric acid form a solid compound which although not a salt is commonly known as naphthalene picrate. If shaken with water it partly decomposes to give solid naphthalene and a solution of picric acid. Bell and Fendley (Trans. Faraday Soc., 1949, 45, 122), measured the e.m.f. at 25 C of the cells  

If the cells a and /J are connected back-to-back the chemical process associated with the flow of electricity will be the transference of solid picric acid from a to /9 where with naphthalene it forms naphthalene picrate. Thus, the value E = 0.090 V is the e.m.f. of the cell  

This method of determining AG was proposed by Bronsted (Z. phj-sikal. Chem. 1911, 77, 284) who attempted the measurements using hydrogen electrodes, but the hydrogen reduced the picric add. By the use of a more indirect electrometric method he obtained — AG = 2.05 kcal mole at 20 °C with a temperature coefficient d AG/dr = — AS = 4 cal deg mole. Brown (J. Chem. Soc. 1925, 345), from cryoscopic measurements in nitrobenzene derived an approximate value of 2.08 kcal mole at 3 C. 

To study the constancy of the equilibrium quotient for the process EtOH + HOAc EtOAc + HOH in the liquid state. 

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