00:01
So this question wants us to predict the spontaneity of the reaction and the temperature dependence of the spontaneity for different combinations of signs of delta h and h for our system.
00:18
So the first situation is if we have a delta h to be negative and that's a h to be positive.
00:35
So to be able to answer this question we have to reflect back on the equation that dg is equal to dlh minus t delta h delta h and we said that a spontaneous process dlt g should be negative okay so if that's a h is negative and delta has is positive so positive times temperature we give us a positive value and negative minus positive value we give us a negative value for delta g so for this particular combination delta h that it is positive and the reaction is spontaneous for the next combination we have delta h is positive and delta h is negative so so going back to this equation, delta g is equal to delta h minus t delta s.
01:48
If delta h is positive minus t and delta s is negative, okay? so negative temperature will give us negative value, multiplied by negative, give us positive.
02:09
So positive plus positive value will give us positive.
02:13
Value for delta g so this reaction will not be spontaneous not spontaneous and that is it for this combination not spontaneous for the next combination we have a delta h is negative it's negative and delta s is negative so write out the equation again delta g is equals to delta h minus t delta h s so if delta h is negative and delta h s is negative what we happen to delta g so negative times temperature will give us negative multiply by negative will give us uh positive then negative minus negative plus positive the answer can be anything so for instance we can have maybe that ih is minus 90 plus since negative that's positive we can have maybe plus 60 or we can have minus 90 in which case 60 is lower than 90 we can have plus 1 -10 so in this case we have a negative 30 and in this case we're going to have 20 positive 20 so the answer for this would depend on what temperature is if temperature is very very very high then this answer will be negative g okay if temperature is high significantly high then delta g will be equals to negative but sorry, if the temperature is significantly high, then delta g will be equal to be equal to positive because here temperature is high.
04:43
So this will be positive.
04:46
And if temperature is small or lower, then delta g will be equals to negative...