Question

In mass production of citric acid, cultures of A. niger are fed on glucose or sucrose to produce citric acid. The citric acid is isolated using calcium hydroxide to yield calcium citrate salt, Ca₃(C₆H₅O₇)₂. To convert back to citric acid, you set up a flow reactor where you flow 122 mg/hr of calcium citrate salt with dilute sulfuric acid, H₂SO₄. The unbalance reaction to obtain citric acid is

H₂SO₄ + Ca₃(C₆H₅O₇)₂ + O₂ --> C₆H₈O₇ + CaSO₄ +H₂O

Balance the chemical reaction and determine the amount of citric acid that will be realized after running the reactor for 8 hrs. What is the minimum molar flow rate of H₂SO₄ and O₂ in the input needed to allow the reaction to completely consume the salt?

After purifying the citric acid obtained in 8-hour shift, you store it in a bicarbonate buffer (10 L). If the initial concentration of the 10 Liters of bicarbonate is 0.002 mol/L H2CO3 and 0.026 mol/L HCO3-, what is the final pH of the storage buffer after addition of the shift’s citric acid? You can assume that the citric acid only deprotonates once with a pKa of 3.14. You want the storage buffer to have a pH greater than 7.1 for long-term stability. Is your process stable, long-term?

Answer 1