Entropy related thermodynamics question

[apsc]

need a bit of help. anything would do, just need to get things started.

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FeS2 in an aqueous slurry is oxidized with 15% pure Oxygen in autoclave:
4FeS2 + 15O2 + 8H2O -> 2Fe2O3 + 8H2SO4

to sustain reatcion, a final temp of at least 220C must be achieved @ oxygen partial pressure of 800kPa

feed slurry is pure pyrite in pure water at 25C, estimate minimum pyrite pulp density (mass % solids)
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the question comes with a chart that shows molecular weight (g/mol) of each compound, the enthalpy (kJ/mol) at 298K of each compound, and the A B C to calculate heat capacity (cp) using the formula:

cp = A + (B*10^-3)T + (C*10^5)T^-2 (J/mol/K)

it also has the formula to calculate water vapour pressure.

i know how to do enthalpy calculations. but i am not sure how i can use the pressure and the temperature to calculate the mass.
any hints / suggestions will be greatly appreciated thanks.

 

[Jhero]

I can offer some guidance on how to approach this problem. First, let's break down the given information and understand what we need to calculate. We are dealing with a chemical reaction that involves the oxidation of FeS2 in an aqueous slurry, and the goal is to achieve a final temperature of at least 220C with an oxygen partial pressure of 800kPa. We also have the molecular weight and enthalpy of each compound involved in the reaction, as well as a formula to calculate heat capacity.

To start, we need to determine the mass of pyrite (FeS2) needed to achieve the desired reaction conditions. To do this, we can use the formula for water vapor pressure to calculate the partial pressure of water in the autoclave. This will give us an idea of the amount of water present in the system. Then, we can use the ideal gas law to calculate the number of moles of oxygen needed to achieve the desired oxygen partial pressure. From there, we can use the stoichiometry of the reaction to determine the number of moles of FeS2 needed.

Next, we can use the given formula for heat capacity to calculate the heat required to raise the temperature of the system to 220C. This will give us an idea of the amount of heat needed to sustain the reaction. Then, we can use the enthalpy values to calculate the heat released by the reaction. By comparing the heat required and the heat released, we can determine the minimum mass of FeS2 needed to sustain the reaction.

Finally, we can use the mass of FeS2 and the known density of the slurry to calculate the minimum pulp density (mass % solids) needed for the reaction. Keep in mind that this calculation assumes ideal conditions and may not account for any losses or inefficiencies in the reaction.

I hope this helps to get you started. Remember to always double check your calculations and assumptions, and don't hesitate to consult with a colleague or supervisor for additional guidance. Good luck!