Chapter 15 Principles of Chemical Reactivity: Equilibria - 15-6 Disturbing a Chemical Equilibrium - Applying Chemical Principles - Questions - Page 582: 2

0.0024 M

The concentration of dimer dissociated is x, the concentration of monomer formed is 2x. $K=(2x)^2/(0.015-x)=4.1\times10^{-4}$ $4x^2+4.1\times10^{-4}x-6.15\times10^{-6}=0$ $x=0.00119\ M$ At equilibrium there will be 0.0024 M of monomer.