Acid rain has a corrosive effect on marble (CaCO_3). CaCO_3 (s)+2H_3O^+ (aq) doubleheadarrow Ca^2+(aq) + 3H_2O(l) + CO_2(g) delta_rG degree (298. 15K) = -56.1 kJ/mol A 100 g sample of CaCO_3 (s) is placed in the solution that is 0.02 M in Ca(NO_3)_2 with a pH of 4.00 under air when temperature is 298.15 K. Air contains 4.0 times 10^-4 bar of CO_2(g). Calculate the value of delta_r G. Is the forward reaction spontaneous? Consider the ionic strength produced by Ca(NO_3)_2 to determine the activity of Ca^2+.