An equilibrium mixture of propanoic acid, CH3CH2COOH and its conjugate base has a pH of 4.87. What form predominates after H3O+ is removed?
After HOW MUCH H3O^+ is removed. If ALL of it is removed, you will be left with the conjugate base ONLY (no acid present).
To determine the form that predominates after H3O+ (hydronium ions) is removed, we need to consider the given information about the pH of the equilibrium mixture.
The pH is a measure of the concentration of hydronium ions in a solution. In this case, since the pH is 4.87, it means that the concentration of hydronium ions is 10^(-4.87) mol/L.
Propanoic acid (CH3CH2COOH) is a weak acid that partially dissociates in water. When it dissociates, it releases hydronium ions (H3O+) and its conjugate base, which is the propanoate ion (CH3CH2COO-). The dissociation reaction can be represented as follows:
CH3CH2COOH ⇌ CH3CH2COO- + H3O+
The equilibrium mixture at pH 4.87 indicates that the concentration of hydronium ions is relatively low. In such cases, according to Le Chatelier's principle, the reaction tends to shift towards the side with fewer hydronium ions, in order to restore equilibrium.
Since removing H3O+ means decreasing its concentration, the forward reaction (formation of hydronium ions) will be favored. This means that the reaction will shift to the left, towards the side of propanoic acid, and the propanoic acid form (CH3CH2COOH) will predominate after H3O+ is removed.
In summary, after H3O+ is removed, the propanoic acid form (CH3CH2COOH) will be the predominant form in the equilibrium mixture.