Answer:
(a) pH = 4.56 is acidic
(b) pH = 10.4 is basic
(c) [OH-] = 2.4x10-8, thus [tex]pH = -Log (4.16x10^{-7}) = 6.3[/tex] is acidic
Explanation:
The pH is the mesure of the acidity or bacisity of a solution. It indicates the concentration of protons in a solution and it is define as:
[tex]pH = -Log ([H^{+}])[/tex]
The scale of pH goes from 1 to 14, being 1 the most acid condition and 14 de most basic condition. Also a pH = 7 is a neutral condition.
Therefore, if the pH is: 1 ≤ pH < 7 the solution will be acidic and if the pH is 7 < pH ≤ 14 the solution will be basic.
To answer (c) it is also necessary to consider the water autoionization to calculate the protons concentration as shown bellow
[tex]K_{w} =[H^{+} ][OH^{-}]=10^{-14}[/tex]
[tex][H^{+} ]=\frac{10^{-14}}{[OH^{-}]}[/tex]
For (c) [OH-] = 2.4x10-8
[tex][H^{+} ]=\frac{10^{-14}}{2.4x10^{-8}}=4.16x10^{-7}[/tex]
And using the definition of pH
[tex]pH = -Log (4.16x10^{-7}) = 6.3[/tex]
