The equilibrium constant K is an expression of the equilibrium concentrations of the molecules or the ions in solution.
ðɪ ˌiːkwɪlˈɪbɹiəm kˈɑːnstənt kˈeɪ ɪz ɐn ɛkspɹˈɛʃən ʌvðɪ ˌiːkwɪlˈɪbɹiəm kˌɑːnsəntɹˈeɪʃənz ʌvðə mˈɑːlɪkjˌuːlz ɔːɹ ðɪ ˈaɪɑːnz ɪn səlˈuːʃən.