( ( pH ( ( A measure ) ( of ( hydrogen-ion concentration ) ) ) ) ( ( in ( a solution ) ) ( , ( ( ( expressed ( as ( ( ( the logarithm ) ( -LRB- ( ( base ten ) -RRB- ) ) ) ( of ( ( the reciprocal ) ( of ( the ( hydrogen-ion concentration ) ) ) ) ) ) ) ) ( in ( ( gram moles ) ( per litre ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN pH) (NP (NP (DT A) (NN measure)) (PP (IN of) (NP (JJ hydrogen-ion) (NN concentration))))) (PP (IN in) (NP (DT a) (NN solution))) (, ,) (VP (VBD expressed) (PP (IN as) (NP (NP (NP (DT the) (NN logarithm)) (PRN (-LRB- -LRB-) (NP (NN base) (CD ten)) (-RRB- -RRB-))) (PP (IN of) (NP (NP (DT the) (NN reciprocal)) (PP (IN of) (NP (DT the) (JJ hydrogen-ion) (NN concentration))))))) (PP (IN in) (NP (NP (NN gram) (NNS moles)) (PP (IN per) (NP (NN litre)))))) (. .)))
pH A measure of hydrogen-ion concentration in a solution, expressed as the logarithm (base ten) of the reciprocal of the hydrogen-ion concentration in gram moles per litre.
(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.