( PH ( ( is ( ( the measure ) ( of ( ( hydrogen ions ) ( in solutions ) ) ) ) ) . ) )
(ROOT (S (NP (NNP PH)) (VP (VBZ is) (NP (NP (DT the) (NN measure)) (PP (IN of) (NP (NP (NN hydrogen) (NNS ions)) (PP (IN in) (NP (NNS solutions))))))) (. .)))
PH is the measure of hydrogen ions in solutions.
(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.