Solutions and colligative properties and chemical kinetisa combined ques.

[sirisha kotik]

a mixture of two miscible liquids a nd b has 10 moles of a and 12 moles of b. pure vapour pressure of a is 300mm Hg and tht of b is 500mm of hg. as soon as b is added to solution A starts polymerising into an insoluble solid. after 100 minutes 0.525 moles of a solute C is added whch stops polymerisation completely.the final vapour pressure of solution is 400 mm hg. calculate rate constant of the polymerisation reaction.

Homework Equations

k=1/t ln(c1/c2) p= p1x X1 + p2x X2

The Attempt at a Solution

ok first calculated the total v.p of inial solution. mole frac. of a is 5/11 and tht of b is 6/11 so total v.p comes to be 300x5/11+500x6/11 whch is equal to 4500/11. after tht by usins pressure is proportional to moles calculated final moles of last solution which is comng abt 21.51 n inial moles are 22. bt ,main problem is i m nt gettng homework to calculate moles of a tht have polymerised. please help.

 

[nate808]

First, let's calculate the initial moles of A and B in the solution. We know that there are 10 moles of A and 12 moles of B, so the total initial moles of the solution is 22 moles.

Next, we can calculate the initial mole fractions of A and B. The mole fraction of A is 10/22 = 5/11, and the mole fraction of B is 12/22 = 6/11.

Now, using the equation p = p1x X1 + p2x X2, we can calculate the initial vapor pressure of the solution. Plugging in the values, we get p = (300 mm Hg)(5/11) + (500 mm Hg)(6/11) = 4500/11 mm Hg.

After 100 minutes, 0.525 moles of solute C is added, which completely stops the polymerization reaction. This means that all of the remaining A has polymerized into an insoluble solid. Therefore, the final moles of A in the solution is 10-0.525 = 9.475 moles.

Using the same equation as before, we can calculate the final mole fraction of B in the solution. The mole fraction of B is now 12/21.475 = 0.560.

Finally, we can use the rate constant equation k=1/t ln(c1/c2) to calculate the rate constant of the polymerization reaction. Plugging in the values, we get k=1/100 ln(5/11)/(12/21.475) = 0.027 min^-1.