( pH ( ( ( was originally ) ( conceived ( to ( be ( ( a measure ) ( of ( ( the ( hydrogen ( ion concentration ) ) ) ( of ( aqueous solution ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN pH)) (VP (VBD was) (ADVP (RB originally)) (VP (VBN conceived) (S (VP (TO to) (VP (VB be) (NP (NP (DT a) (NN measure)) (PP (IN of) (NP (NP (DT the) (NN hydrogen) (NN ion) (NN concentration)) (PP (IN of) (NP (JJ aqueous) (NN solution))))))))))) (. .)))
pH was originally conceived to be a measure of the hydrogen ion concentration of aqueous solution.
(ROOT (S (NP (NP (DT The) (NN concentration)) (PP (IN of) (NP (NP (DT the) (NN hydrogen) (NN ion)) (PP (IN in) (NP (DT a) (NN solution)))))) (VP (MD can) (VP (VB be) (VP (VBN calculated) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN ph)) (VP (VBZ is) (VP (VBN known)))))))) (. .)))
The concentration of the hydrogen ion in a solution can be calculated when the ph is known.