( ( The ( activity coefficient ) ) ( ( is ( ( that number ) ( which ( ( , ( ( when ( multiplied ( by ( ( ( the ( actual pressure ) ) or ) concentration ) ) ) ) , ) ) ( ( gives ( ( the activity ) ( of ( the substance ) ) ) ) ( as ( it ( is ( under ( conditions ( of ( ( ( low pressure ) or ) ( low concentration ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN activity) (NN coefficient)) (VP (VBZ is) (NP (NP (DT that) (NN number)) (SBAR (WHNP (WDT which)) (S (PRN (, ,) (SBAR (WHADVP (WRB when)) (S (VP (VBN multiplied) (PP (IN by) (NP (NP (DT the) (JJ actual) (NN pressure)) (CC or) (NP (NN concentration))))))) (, ,)) (VP (VBZ gives) (NP (NP (DT the) (NN activity)) (PP (IN of) (NP (DT the) (NN substance)))) (SBAR (IN as) (S (NP (PRP it)) (VP (VBZ is) (PP (IN under) (NP (NP (NNS conditions)) (PP (IN of) (NP (NP (JJ low) (NN pressure)) (CC or) (NP (JJ low) (NN concentration)))))))))))))) (. .)))
The activity coefficient is that number which, when multiplied by the actual pressure or concentration, gives the activity of the substance as it is under conditions of low pressure or low concentration.
(ROOT (S (NP (NP (DT The) (NN number)) (PP (IN of) (NP (NP (NNS particles)) (PP (IN of) (NP (NP (DT a) (NN substance)) (PP (IN in) (NP (DT a) (VBN given) (NN volume)))))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (DT the) (NN concentration))))) (. .)))