Please show all work. We are interested in increasing the concentration of a 3L

Question

Please show all work.

We are interested in increasing the concentration of a 3L methanol-water mixture that contains 20% by volume of methanol. The liquid mixture which is initially at 25 degree C is heated to 65 degree C in the still which is connected to other units as shown. Initial pressure is at atmospheric condition. The entire assembly is completely sealed so that no vapors escape. Then vapors are condensed in a condenser by continuously circulating large amount of cold water at 25 degree C. Liquid is collected as a condensate. What is the molarity of methanol What is the mole fraction of methanol What is the mass fraction of methanol What is the average density What is the average molecular weight

Explanation / Answer

Basis:1 mol of methanol-water solution

Volume %=mole % for aqueous solutions

Molarity=moles/volume in L=(0.2 mol/3L)=0.067 M

Mole fraction of methonal=0.2

Mass of methanol=0.2 mol/32 g/mol=0.00625 g

Mass of water=0.8 mol/18g/mol=0.0444 g Total mass=0.05065 g

mass fraction of methanol=0.00625 g/0.05065 g=0.1239

Average molecular weight=(0.2*32g/mol)+(0.8*18g/mol)=20.8 g/mol

density at 25C=PM/RT=(1 atm*20.8g /mol)/(0.0821 atm L/mol K*298 K)=0.85 g/L

density at 65 C=PM/RT=(1 atm*20.8g /mol)/(0.0821 atm L/mol K*338 K)=0.7495 g/L

Average density=(0.85+0.7495)/2=0.799 g/L

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---

---

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