How does the sun rise and set on the spring and fall equinox

Actually, the Sun only rises due east and sets due west on 2 days of the year  the spring and fall equinoxes! On other days, the Sun rises either north or south of "due east" and sets north or south of "due west." ... At the fall equinox, the Sun rises due east and sets due west.

Explanation:

Sunrise and Sunset - Stanford Solar Center

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.