How does pH change during titration?

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How does pH change during titration?

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Answer 1 · 2015-10-06T19:57:50

It depends.

Explanation:

If we consider the titration of an acid by a base, the pH will increase. However, if we titrate a base by an acid, the pH will decrease.

Example:
Let us consider the titration of $1 M$ $1M$ $H C l$ $HCl$ by $1 M$ $1M$ $N a O H$ $NaOH$ .
The initial pH of the acidic solution $H C l (a q)$ $HCl(aq)$ is around $1$ $1$ . This is resulting from the high concentration of $[H^{+}]$ $[H^+]$ .

When $N a O H$ $NaOH$ is added to the solution, the $O H^{-}$ $OH^-$ ions from $N a O H$ $NaOH$ will react with the $H^{+}$ $H^+$ ions from $H C l$ $HCl$ to form water $H_{2} O$ $H_2O$ according to the following reaction:

$H^{+} + O H^{-} \to H_{2} O$ $H^+ +OH^(-)->H_2O$

Since the $[H^{+}]$ $[H^+]$ is decreasing and knowing that the $p H = - log [H^{+}]$ $pH=-log[H^+]$ the $p H$ $pH$ will increase until neutralization where the $p H = 7$ $pH=7$ . If we continue adding $N a O H$ $NaOH$ the $p H$ $pH$ will continue increasing until reaching a maximum value of $p H = 14$ $pH=14$ .

Here is a video explaining titration of an acid by a base, including the stoichiometry.

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How does pH change during titration?

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