( pH ( ( is ( ( the measure ) ( of ( hydrogen ( ions concentration ) ) ) ) ) . ) )
(ROOT (S (NP (NN pH)) (VP (VBZ is) (NP (NP (DT the) (NN measure)) (PP (IN of) (NP (NN hydrogen) (NNS ions) (NN concentration))))) (. .)))
pH is the measure of hydrogen ions concentration.
(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.