Shortcut for determining acidity/basicity of salts

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Niveda_Tennety_1H
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Joined: Wed Sep 21, 2016 2:59 pm

Shortcut for determining acidity/basicity of salts

Postby Niveda_Tennety_1H » Sun Nov 27, 2016 2:03 pm

Does this shortcut to determine the acidity/basicity of salts always work?
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Matt_Coopersmith_4H
Posts: 20
Joined: Wed Sep 21, 2016 2:57 pm

Re: Shortcut for determining acidity/basicity of salts

Postby Matt_Coopersmith_4H » Mon Nov 28, 2016 3:05 pm

So, the shortcut will work for equations with equal molarity of acids and bases. For those with equal molarities:

Strong Acid + Weak Base = Acidic Solution
Weak Acid + Strong Base = Basic Solution
Strong Acid + Strong Base = Neutral Solution

An explanation can be as followed:

Let’s look at the first example that includes Chromium Hydroxide and Hydrobromic Acid.

Chromium hydroxide is a weak base and therefore only partially disassociates. Therefore, only a fraction of the initial concentration of the base will be present in the aqueous solution as OH-

Hydrobromic acid, however, is a strong acid. Therefore, the acid will completely disassociate, resulting in the initial concentration of the acid to be present in H+ ion concentration.

Therefore, there will be much more H+ in the solution than OH-, resulting in the overall concentration of the solution to be acidic.

WARNING: This will only work for specific concentrations of acids and bases. A solution with a very small molarity of a strong acid and a very large molarity of a weak base will produce a basic solution. In situations where the molarities do not equal one another, it is safest to use equilibrium concentrations to find the actual concentrations of hydroxide and hydronium, and find the pH of the resultant solution.

Hope this helps!


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