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. In order to carry out an anaerobic fermentation, a saturated solution of bariu

ID: 714836 • Letter: #

Question

. In order to carry out an anaerobic fermentation, a saturated solution of barium hydroxide is used in a trap. The barium hydroxide reacts with the carbon dioxide produced from the fermentation yielding a precipitate of barium carbonate, while no air is allowed into the system. How many grams of barium carbonate would you expect to collect from the fermentation of 35.00 g of sucrose at 65.0 % efficiency and at 23.8 oC and 1.23 atm? Assume all CO2 is trapped as barium carbonate. Assume that we have 10.0 mL of 0.750 M barium hydroxide in the trap, calculate the pH of this solution. You can carry out your calculation assuming you are finding the pH before any of the barium hydroxide solution reacts with the carbon dioxide.

Explanation / Answer

a)

moles of sucrose = 35 / 342.2965 = 0.10225 moles

since 1 mole of sucrose produced 4 moles of CO2 during fermentation

so for 100 % efficiency total moles of CO2 will produce = 4*0.10225 = 0.409 moles

so for 65 % efficinecy

moles of CO2 will produced = (0.409 / 100 ) * 65

= 0.2659 moles of CO2 will produced will react with Ba(OH)2

Ba(OH)2 + CO2 ----> BaCO3 + H2O

moles of BaCO3 produced = 0.2659 moles

mass of BaCO3 produced = 0.2659 * 197.34 = 52.463 g

b) [ Ba(OH)2] = 0.75 M

since barium hydroxide has two hydroxide ion

so [OH-] = 2*0.75 = 1.5 M

[H+] [OH]=1.0×1014M
[OH]= 1.5 M
[H+]= 6.67*10^-15 M

pH = -log ( 6.67*10^-15 ) = 14.17