4. Solution Thermodynamics [40 total] a) At what partial pressure of nitrogen (in atm) does a metal become saturated in nitrogen if the metal is held at: 1) atmospheric pressure; and 2) in a vacuum at 1 torr. [10] b) Given the thermodynamic data on page 3, calculate the solubility limit of nitrogen in steel in ppm at 1600C if: 1) the steel is held in a ladle at 1 atm; and 2) if the steel is held in a ladle under a vacuum environment of 1 torr? [20] c) Write the general expression for the activity of gas in solution in a metal relative to a Henrian 1 wt% standard state. If you assume that the nitrogen in the steel is behaving ideally, what is the activity of nitrogen in solution in the steel at its solubility limit relative to a Henrian 1 wt% standard state for the two cases you calculated in (b)? [10] [1] H2O, H,O(8 (1) [2] [N]1 wt%,Fe,1 HEN2,9 AG1 = 41,086.88-110.12T joules/mole AG2= -3590 -23.89T joules/mole R= 8.3141 joules/degree/mole 2 = log(f; )= e}wt%2+e? wt%3+e, wt%4 +... K =exp(-46/R/T) Ph20 RH% -- 100 PH2O 1 torr 0.00132 atm