( ( pH pH ) ( ( is ( ( a measure ) ( of ( ( the acidity ) ( of ( the water ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN pH) (NN pH)) (VP (VBZ is) (NP (NP (DT a) (NN measure)) (PP (IN of) (NP (NP (DT the) (NN acidity)) (PP (IN of) (NP (DT the) (NN water))))))) (. .)))
pH pH is a measure of the acidity of the water.
(ROOT (S (NP (NP (DT The) (NN acidity)) (PP (IN of) (NP (DT a) (NN solution)))) (VP (VBZ is) (ADVP (RB typically)) (VP (VBN assessed) (ADVP (RB experimentally)) (PP (IN by) (NP (NP (NN measurement)) (PP (IN of) (NP (PRP$ its) (NN ph.)))))))))