400cm³ of dry air was passed over heated copper powder in a hard glass tube until no further change. What volume of remained at the end of the experiment?

Explanation:

I think there' will be a decrease in volume of the air.

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.

if you're asking what comes out, it's steam.