Correlation of Limiting Currents under Free Convection Conditions

Limiting currents were measured for deposition of copper on plane vertical cathodes from unstirred solutions. Electrolyte composition ranged from 0.01 to 0.7 molal , 1.38 to 1.57 molal , and 0 to 6.38 molal glycerol. Cathode heights varied from 0.25 to 3.0 in. Limiting current densities were from 0.4 to 108 ma/cm 2 . A general correlation of the data may be represented by the equation: are the mass transfer Nusselt, Schmidt, and Grashof numbers, respectively. This result is in good agreement with that predicted from the boundary layer theory for mass transfer by free convection.