In: Chemistry
Select the statements below that are false and think about why they are not true. a) If a chemical reaction is spontaneous then the ?Ssys must always be positive. b)If a chemical reaction with a negative ?Ssys is spontaneous then ?Ssurr must be positive. c) If a chemical reaction is spontaneous then the ?Euniv must be increasing. d) We don\'t need to worry about spontaneous reactions because they are rare.
a) if the reaction is spontaneous, then the increase of entropy in the universe is ALWAYS positive... But we are now talking about the system...
Since:
S universe = S suroundings + S system
We could still have a very negative change in the suoundings, the S of system may be either + or - and would not matter
a) answer is NOT must be always positive
b) That is TRUE, since once again:
S universe = S suroundings + S system
S universe must be ALWAYS positive
If S system is negative, you must have S suroundings positive and a big number!
c) I will supose "?Euniv" is enthalpy
The nature of the reaction's enthalpy does not says if the rection will or will not be possible (we only care about entropy right now) If it is endothermic or exothermic will not care!
d) We DO need to study them because they are the ones that actually occur in real life, non-spontaneous actually don't exist in this universe!