Weak vs strong acids
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Weak vs strong acids
Why do solutions of weak acids have higher pH values than solutions of strong acids at the same concentration?
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Re: Weak vs strong acids
strong acids dissociate fully, therefore when a concentration like 0.1 M of a strong acid would lead to 0.1 of the hydrogen ions. However, weak acids don't fully dissociate, therefore 0.1 M of a weak acid would lead to less than 0.1 M of the hydrogen ions. When a pH is higher, that means its more basic. Stronger acids have lower pH levels, therefore weak acids have high pHs compared to strong acids
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Re: Weak vs strong acids
Lower pH indicates that an acid is strong. Because pH is the -log of the concentration of hydronium ions, low pH means a high concentration of hydronium or H+ ions. Weak acids have a lower concentration of hydronium ions, thus taking the -log will give us a higher pH.
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Re: Weak vs strong acids
Strong acids dissociate completely and have a higher hydrogen ion concentration, weak acids partially dissociate and have a lower hydrogen ion concentration. Because pH=-log[H+], you would find that the pH of the weak acid would be higher than the pH of the strong acid. Higher pH values are more basic while lower pH values are more acidic.
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Re: Weak vs strong acids
Strong acids dissociate completely while only a portion of weak acids dissociate so the final H+ concentrations would be different even if they started with the same initial concentrations.
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Re: Weak vs strong acids
The stronger acid will dissociate completely and therefore the concentration of hydrogen ions will be higher. A higher hydrogen ion concentration results in a lower pH.
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