Question

The question, basically, is why do some things mix freely, while others don’t, when put together under conditions of constant temperature and pressure. Address each of the following questions, briefly:

a. For mixing to occur, what kind of value does delta Gmix need to have?

b. How is Gmix related to Hmix and Smix ?

c. What kind of value would Hmix have for an ideal solution?

d. What kind of value would Smix have for an ideal solution?

e. What does all that imply about whether ideal solutions will mix spontaneously?

f. Which term, Hmix or Smix , is most likely to change from the ideal value in a real solution?

g. What relationship between Hmix and Smix will prevent mixing from happening in a real solution?

Answer 1

a) delta Gmix = negative

b) $\Delta$ Gmix is negative and   $\Delta$ ​Hmix is negative and   $\Delta$ ​Smix positive

from   $\Delta$ ​Gmix =   $\Delta$ ​Hmix - T   $\Delta$ ​Smix relation we get   $\Delta$ ​Gmix negative for spontaneous process

c) for ideal solution $\Delta$ ​Hmix = 0

d)   $\Delta$ ​Smix = 0 for ideal solution

e) for ideal solution mixing

   $\Delta$ ​Hmix = 0

$\Delta$ ​Vmix = 0

P_A = P⁰_A X_A

P_B = P⁰_B X_B

f) $\Delta$ ​Hmix changes into positive

$\Delta$ ​Smix chnages into negaitve