Please correct the values for , the magnitude is correct but the sign should be negative because, = - RTlnKsp. As R, T and lnKsp are positive values so, value of should have been negative.
Answer 1 a)
Spontaneity of a reaction depends on , if this value is positive, reaction is non spontaneous. If it is negative, reaction is spontaneous.
As value of is negative at all temperatures, the reaction is spontaneous at all temperatures.
Answer 1 b)
Reaction for which is positive is said to be endothermic. If it is negative, then the reaction is exothermic.
As the calculated value of is positive, the reaction is endothermic i.e. it requires heat.
Answer 1 c)
Value of is positive in all cases i.e. entropy increases with dissolution.
This is as per expectation because from the equation:
KNO3 (s) + H2O(excess) --------> K+ (aq.) + NO3- (aq.)
It is clear that the ions are free to move in aqueous medium i.e. in disordered state but before dissolution, these ions were restricted to lattice point i.e. ordered state. So, dissolution has increased randomness or disorder, which would result in positive value of .
can be calculated as:
= SK+ + SNO3- - SKNO3
Answer 2
For those compounds whose solubility decreases with increase in temperature,
value of will decrease (becomes less negative) with increase in temperature.
will be negative i.e. reaction would be exothermic, it will release heat on dissolution.
values would have increased with increase in temperature just like KNO3 because the ions will get kinetic energy
Answer 3 a)
Assumption made is that the solution becomes saturated with KNO3 at this temperature and the solid is in equilibrium with the solution.
Answer 3 b)
If the assumption was not true, equilibrium would not have been achieved. So, Ksp value calculated would have been lesser than actual value and hence calculated would not have been lesser in magnitude in comparison to actual.
THER 112 The Themodynamics of Porasiun Nirate DingWe Post-Laboratory Questions (Use the spaces pr...
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