# Entropy of universe for non spontaneous processes

When spontaneous processes are accompanied with an increase in entropy of universe and remains unchanged in a reversible process, what happens to entropy when one process is non spontaneous? Would entropy decrease??

• Yes. Don't take the second law to mean that these non-spontaneous reactions can never happen. They can happen. They are just statistically speaking extremely unlikely to happen. Oct 14, 2015 at 11:42
• What are you referring to when you use the term "non-spontaneous?" Please define this term so that we are all on the same page. Oct 14, 2015 at 17:38
• @chester miller, this is a question from Brown's Chemistry The central science 13th ed. Page 827. The question is just as simple as that. And the answer is no. Oct 14, 2015 at 17:57
• @orthocresol Please see my comment on Costa's answer, below. And just to paint a picture of how large 10^(2 x 10^23) is, consider that there are estimated to be ~10^80 atoms in the observable universe. If there were one of our universes for every atom, then the total number of atoms in those 10^80 universes would be "only" 10^160. Now suppose you do it again, where each atom represents 10^80 universes. Then you've only made it to 10^240 atoms. You would have to repeat this process (of expanding atoms into universes) 8.2 x 10^20 times before you would reach 10^(2 x 10^23) atoms! Sep 13, 2020 at 7:22