Please SHOW ALL WORK and calculations. I answered the part ii but not sure if it

Question

Please SHOW ALL WORK and calculations. I answered the part ii but not sure if it's correct so please answer both parts of the question.

4. (10 points) The data below are experimentally determined by various authors (see for example Davison et al., 1991) plotted as [Fez versus pH for amorphous iron (Fes) at og data with numbers (in 298 K and P H25 10 atm. The various aged refer to hours) iron sulfide precipitate samples. (i) What solubility constant Kip can be derived for from these data for the reaction Fes (amorphous solid) 2H Fe H2S(g) (ii) How does the solubility change with age of the precipitated Fes? We ccw see tram Hu graph that pt. 150 has a Hesser value as ecmpa points -1o sa Twenee re precipitated Fes increases. solubility f Fes decreases 750 106 20 pH Page 5 of 6

Explanation / Answer

Expression for Ksp = [Fe2+]*pH2S / [H+]2

The point ( 3.7 , 3.4) lies on the graph. ( This is the best approximation I could make from the graph . You can make a better approximation by properly scaling the graph ).

pH = 3.7 means [H+] = 10-3.7

-log [Fe] = 3.4 means [Fe2+] = 10-3.4

Putting values we get:

Ksp = 1

We can see from the graph that data point with time value 750 has a lesser Ksp value as compared to the points 70 ( or even 20 )

Thus as the time of precipitated FeS increases, solubility of FeS decreases.

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