( ( For ( a ( small ( reaction rate ) ) ) ) ( , ( ( the overpotential ) ( ( is small ) ; ) ) ) )
(ROOT (S (PP (IN For) (NP (DT a) (JJ small) (NN reaction) (NN rate))) (, ,) (NP (DT the) (NN overpotential)) (VP (VBZ is) (ADJP (JJ small))) (: ;)))
For a small reaction rate, the overpotential is small;
(ROOT (S (NP (NP (DT The) (NN difference)) (PP (IN between) (NP (NP (DT the) (JJ theoretical) (JJ half-reaction) (NN reduction) (NN potential)) (CC and) (NP (NP (DT the) (JJ actual) (NN voltage)) (VP (VBN required)))))) (VP (VBZ is) (VP (VBN called) (S (ADJP (JJ overpotential))))) (. .)))