An equilibrium mixture at 425°C is found to consist of 0.00183 mol/L of H2, 0.00313 mol/L of 12, and 0.0177 mol/L of HI. Write the equilibrium expression and solve for Keq for the
reaction H2(g) + 12(g) + 2HI(g).

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.