Question

When KNO3 is dissolved in water, the resulting solution is significantly colder than the water was originally.

(a) What conclusions can you draw about the intermolecular attractions involved in the process?

(b) Is the resulting solution an ideal solution?

Answer 1

a)

If it gets colder, this implies temperature decrease.

If this is true, then the reaction is ENDOthermic, meaning that the solution will absorb heat from the surroundings

b)

Not likely, ideal solutions will not have increase/decrease in temperatures.... recall that in dissolution:

Step 1: solute breaks apart; this is Endothermic.

Step 2: solvent breaks apart. this is Endothermic.

Step 3: Solvent and Solute bond, this is Exothermic

Recall that

Hdissolution = H1 + H2 + (-H3)

Therefore, if H1+H2 > H3, this will be endothermic

If H1 + H2 < H3, this will exothermic process

If H1 + H2 = H3, this will be ideal solution