For the electrochemical cell,
$$Mg(s) \mid Mg^{2+}$$ (aq,1M) $$\parallel Cu^{2+}$$ (aq,1M) $$\mid Cu(s)$$ the standard emf of the cell is 2.70 V at 300 K. When the concentration of $$Mg^{2+}$$ is changed to 𝒙 M, the cell potential changes to 2.67 V at 300 K. The value of 𝒙 is ____.
(given $$\frac{F}{R} = 11500 KV^{-1}$$, where F is the Faraday constant and 𝑅 is the gas constant, $$\ln(10) = 2.30)$$