Acid Base PH, POH

Question

A solution contains 0.00568 M HCl. Determine the [H3O^+] for the solution

Calculate the [OH^−]

Answer 1

Howdy! So if we want to solve this problem we have to remember a few things. First off, the chemistry involves HCl (hydrochloric acid) which acts as a strong acid - meaning it will dissociate completely when put into solution. So the equation should read HCl --> H+ + Cl-. The second thing to remember is that HCl is a monoprotic acid - meaning it only gives off one proton when put into solution. So if you have a 0.00568 M HCl solution, we are being told there is 0.00568 moles of HCl per 1 liter of solution. Because we know there is a 1:1 ratio between HCl and H+, we can say our [H+] or hydrogen ion concentration will also equal 0.00568 M.

To determine the [OH-] we need to remember the formula: Kw = [H+] * [OH-] where Kw = 1.0 x 10^-14. So we have 1.0 x 10^-14 = 0.00568 M x [OH-]

[OH-] = 1.0 x 10^-14/0.00568M = 1.76 e-12 M OH-