chem helpppp?

Question

ethanol and water are completely miscible (they dissolve in each other in all proportions)

when the two substances are mixed, is randomness increased or decreased?

heat is liberated in the dissolving process. does the tendency toward minimum energy favour the separated pure substances, or the solution of one in the other?

why are they completely miscible?

Answer 1

When two substances are mixed, a lot of the time randomness is increased, however, when you dissolve salt in water, the water forms a hydrated cage around each cation and anion, this actually orders the water molecules and randomness can actually be decreased. So there is no hard and fast "it alaways is this". Unfortunately that's what chemistry is about!

If heat is given off, then the final state was lower in energy than the initial state - the final state was the solution, the initial state was separated species. So minimum energy in this case is the solution

Miscibility has to do with entropy. It tends to be an entropy driven process. If you can mix two species together and they form a homogenous mixture, then they are miscible. I would say that you would be hard pressed to just be able to look at two species and predict - oh those would be miscible as opposed to oh, that will dissolve. When species are miscible, there will be no visible "dividing line" between them - e.g. no meniscus. It will be as if you have one liquid. Or one gas present (gases are also miscible), or one solid (not many solids do this). Again, this is something that is not visual (obviously) so when you have a mixture of miscible things, you might think it is a pure substance!

Answer 2

randomness is increased because a water molecule forms 4 bonds with an another water molecule(2 through hydrogen and two through oxygen. ) but when it is mixed with ethanol it forms only two polar bonds. so as attractive forces are weaken the molecule becomes more free and hence randomness increases.

a system always wants to go to a thermodynamically more stable state and a state of minimum energy is such a state. so it is thermodynamically favored .

always remember a thumb rule" like dissolves like".
water and ethanol both have similer types of dipole - dipole interactions or hydrogen bonding you can say as due to high
electronegitivity of oxygen as compared to hydrogen a partial -ve charge develope on oxygen and a partial + charge develops on hydrogen and hence they can attract the opp.
chaged parts of the other molecules.

Answer 3

Randomness is increased.

Solution is favoured.

They are miscible due to hydrogen bonding.

Answer 4

randomness is increased.

Solution is favoured