A gas absorption unit is being used to remove carbon dioxide from air by absorpt

Question

A gas absorption unit is being used to remove carbon dioxide from air by absorption into water. The mole fraction of CO2 in air at the inlet is 0.2 and the flow rate of the gas stream is 100 l/min. It is desired to remove 95 % of the CO2 in the gas stream. If pure water enters the column at a flow rate of 10 g/min, what is the mole fraction of CO2 in the liquid stream exiting the bed? You take 5 cc of this solution. How many cc’s of 1 M NaOH solution would be needed to neutralize the solution? MWNaOH=40 g/mol A gas absorption unit is being used to remove carbon dioxide from air by absorption into water. The mole fraction of CO2 in air at the inlet is 0.2 and the flow rate of the gas stream is 100 l/min. It is desired to remove 95 % of the CO2 in the gas stream. If pure water enters the column at a flow rate of 10 g/min, what is the mole fraction of CO2 in the liquid stream exiting the bed? You take 5 cc of this solution. How many cc’s of 1 M NaOH solution would be needed to neutralize the solution? MWNaOH=40 g/mol

Explanation / Answer

Assuming the absorption takes place at isothermal conditions.

The flow rate of CO2 in the inlet= 100*0.2= 20 l/min

It is desired to remove 95% of CO2. CO2 to be removed= 20*0.95= 19 l/min

CO2 remaining = 20-19 =1 L/min

Flow rate of CO2 in the liquid stream =19 l/min

Assuming a liquid density of 1, flow rate of CO2 in the liquid= 19 *1000cc/min*1g/cc = 1900g/min

Molar mass of CO2= 44 gm, moles of CO2 in liquid stream = 1900/44 = 43.18 gmoles/min

Flow rate of water= 10 g/min , flow rate of water = 10/18= 0.55 gmoles/min

Mole fraction of CO2 in the exit stream = 43.18/(43.18+0.55)= 0.987

Mass of 5cc of solution = 5 gm

Mass of CO2 in 5 gm = 5*1900/(1900+10) = 4.97 gm, moles of CO2= 4.97/44 =0.1129

H2CO3+ NaOH-> Na2CO3 + H2O

Moles of NaOH is same as moles of NaOH = 0.1129

Volume of NaOH= moles/Molarity = 0.1129/1 L =0.1129 L

Volume of NaOH in cc = 0.1129*1000ml =112.9 cc

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.