For the electrochemical cell,
Mg(s)|Mg2+(aq, 1M)||Cu2+ (aq, 1M) | Cu(s)
the standard emf of the cell is 2.70 V at 300 K. When the concentration of Mg2+ is changed to x M, the cell potential changes to 2.67 V at 300 K. The value of x is____.
(given, F/R = 11500 KV–1, where F is the Faraday constant and R is the gas constant, ln(10) = 2.30)