pH scale vs chemical science

pH scale and chemical science both are nouns.

Word	Noun	Adjective	Verb	Adverb
pH scale	Yes	No	No	No
chemical science	Yes	No	No	No

pH scale (noun)	chemical science (noun)
(from potential of Hydrogen) the logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter; provides a measure on a scale from 0 to 14 of the acidity or alkalinity of a solution (where 7 is neutral and greater than 7 is more basic and less than 7 is more acidic)	the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions