Salt Solutions

[Annie 1H]

when calculating the pH of a salt, how do we determine what equation to write.
for example: salt + water —> h3o+ or oh- + conjugate base or conjugate acid

[lapalla]

When the salt is acidic then H30+ and a conjugate base are formed. When a salt is basic then OH- and a conjugate acid are formed.

[Jonathon Jauregui]

Expanding off of what Iapalla said,

You can determine which equation to right based on the Salt being dissolved and leaving the ions separate
For example: NaClO +H2O
*(Since we know that NaClO is the salt in the situation we can rewrite it as Na+ ClO- because it can be dissolved in water. Then we know that Na is the conjugate acid of a strong base Na(OH) so the Na will remain in that form since it is stable in that form, but ClO- is the conjugate base of a weak acid HClO, meaning that the weak acid needs Hydrogen to become in a more stable form. Meaning that it will take positive hydrogen ions from the water leaving it as OH- while the ClO- becomes HClO a weak acid.)
--> Rewrite the Equation as NaClO + H2O -><- HClO + OH-

* Essentially the main takeaway is that if there is a conjugate base of a weak acid in the salt as the reactions it will take hydrogen from water, producing hydroxide ions (OH-)
* Then the same can be said with finding a conjugate acid of a weak base in the salt, then you can tell that the conjugate acid will give hydrogen to the water, creating Hydronium ions (H3O+)

Hope this helps.