Is this thermo process reversible?

[hadroneater]

Homework Statement

If 0.8kg of water at 100 celsius is mixed with 0.8kg of water at 0 celsius, is this process reversible?

Homework Equations

Entropy:
S = mcln(T_2/T_1)

The Attempt at a Solution

I've already calculated the entropy of the process, which is 81.1 J/K. But how do I know if it's reversible?

 

[vigintitres]

How can it be reversible if entropy is generated? Entropy is generated for irreversible processes right? I think I remember this, but correct me if I'm wrong.

 

[hadroneater]

Oh. I seemed to have skipped that part of the lecture. Thank you!