Identify three examples of situational irony in "The Story of an Hour" by Kate Chopin.

This story is a great one to use when discussing irony,
because it is full of it, to be sure.  In situational irony, you are looking for
examples that demonstrate that life often hands us things that are entirely the opposite
of what was expected, and that are beyond our control.  It often demonstrates how little
power humans have over events in their lives, or sometimes even over our reactions and
emotions.  So, based on that, here are some examples from the
story.

1.  Brentley Mallard, whose name had been on a list
of the dead, turns out to actually be alive.  First of all, there is irony in him dying
in a fluke train accident in the first place; then, once the characters are finally
accepting his death and getting used to the idea, he walks in the door.  No one would
have expected that, and it is a huge shock to everyone.

2. 
The ending, when Louise dies, supposedly of "a joy that kills," is actually ironic,
because we know better.  We know that she wasn't joyful that her husband was alive; in
fact, we know that she had felt repressed and miserable in her marriage and that
Brentley's death had liberated her from those chains.  So, it is ironic that she would
have a heart attack, not when she learned that he was dead (as in the beginning), but
when she learned that he was alive.  The doctor ironically concludes it was joy that
killed her; that is not very likely.

3.  Louise's reaction
to the news of her husband's death was unexpected, and even a bit surprising to her. 
She feld "freedom!" and "joy" at the news.  This is an unlikely and surprising result;
not grief, not mourning, but joy.  That just goes to show how life is often surprising,
and can't be fit into nice little predictable categories.

I
hope that helped; good luck!