How do acids become alkaline over time? In the experiment a zinc washer was added to hydrochloric acid. The first pH read 0 and at t=14 days, it read 5. Why?

1 Answer
Jun 28, 2017

It is not acids that became alkaline; it occurred a reaction between HCl and Zn:#2HCl + Zn = ZnCl_2 + 2 H_2#
at the beginning you can see fizz because of Hydrogen that is released in the solution. The reaction stopp itself when the remained amount of HCl is very small (pH =5 means #H^+ = 10^(-5) M#)