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Topic: i need help with a VERY confusing stoichiometry question  (Read 10052 times)

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Whwang

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i need help with a VERY confusing stoichiometry question
« on: July 24, 2006, 09:52:11 PM »
Bacterial digestion is an economical method of sewage treatment. The reaction 5CO2 + 55NH4 + 76O2 ---> C5H7O2N + 54NO2 + 52H2O +109H is an intermediate step in the conversion of nitrogen in organic compouinds into nitrate ions. How much bacterial tissue is produced in a treatment plant for every 1.0 x 10^4 kg of wastewater containing 3.0% NH4 ions by mass? Assume that 95% of the ammonium ions are consumed by the bacteria.

Um, i know that you're always supposed to start with the givens, but i just don't know how to begin the setup. Will someone guide me/help me figure out how to do this?

Offline Albert

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Re: i need help with a VERY confusing stoichiometry question
« Reply #1 on: July 25, 2006, 03:11:41 AM »
I'm not sure to have understood the problem (I guess because of my poor English). Do bacteria react with 104 Kg of a 3% solution of NH4+? And, if that's how things are, what product represents bacterial tissue?

Offline Will

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Re: i need help with a VERY confusing stoichiometry question
« Reply #2 on: August 02, 2006, 02:43:14 PM »
Bacterial digestion is an economical method of sewage treatment. The reaction 5CO2 + 55NH4 + 76O2 ---> C5H7O2N + 54NO2 + 52H2O +109H is an intermediate step in the conversion of nitrogen in organic compouinds into nitrate ions. How much bacterial tissue is produced in a treatment plant for every 1.0 x 10^4 kg of wastewater containing 3.0% NH4 ions by mass? Assume that 95% of the ammonium ions are consumed by the bacteria.

I'm assuming the C5H7O2N is the bacterial tissue.
To work out the answer you can work out the mass of ammonium consumed (10000000 x 0.03 x 0.95) which can be converted to moles of NH4+ consumed by dividing by the Mr(18.0386).
Now that you know the moles of ammonium consumed you can work out the moles of bacterial tissue by dividing by 55.
To convert that into grams you just have to multiply by the Mr(113.1153).
I got 32493.8g of bacterial tissue as the answer, hope that's right!

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