Table 2. Summary of Reaction Parameters and Their Effects 



Parameter 



Influence 



Effect on the Reaction 



Electrode gap 



Cell internal 



Decreasing gap increases 





resistance 



reaction rate. Small 

 gap can cause the 





Free transport 

 of reaction 



products to clog the 





products 



gap which excludes 

 the electrolyte from 

 anode surface, thus 

 reducing the reaction 

 rate. 



Electrolyte 



Transport of ions; 



Raising temperature 



temperature 



solubility of 



increases reaction 





products 



rate; no noticeable 

 effect on energy 

 density. 



Electrolyte pH 



Rate of pre- 



High pH can cause an 





cipitation of 



Mg(OH). barrier to form 

 near anode, which excludes 





Mg(OH)„ near the 

 anode 





the electrolyte, thus 







reducing the reaction 







rate. 





Evolution of H_ 

 at the cathode 



Low pH (excess H ions) 





promotes the formation 







of H„ at the cathode, 

 increasing the reaction 











rate. 



Electrolyte 



Transport of 



An electrolyte thick- 



density 



reaction products 



ened with reaction 

 products slows the 

 transport of fresh 

 electrolyte to the 

 electrodes, thus 

 reducing the reaction 

 rate. Also reduces i 

 removal of products ' 

 and increases pH 

 at anode. 



continued 



52 



„v „ iSm-mmmmamm«~ 



