https://wikimd.org/index.php?action=history&feed=atom&title=Acid_dissociation_constant
Acid dissociation constant - Revision history
2026-04-26T02:19:19Z
Revision history for this page on the wiki
MediaWiki 1.44.2
https://wikimd.org/index.php?title=Acid_dissociation_constant&diff=6324489&oldid=prev
Prab: CSV import
2025-02-18T11:51:09Z
<p>CSV import</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 11:51, 18 February 2025</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l75">Line 75:</td>
<td colspan="2" class="diff-lineno">Line 75:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Acid-base chemistry]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[[Category:Acid-base chemistry]]</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"><gallery></ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Acetic-acid-dissociation-3D-balls.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:PK_acetic_acid.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Weak_acid_speciation.svg|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:H3PO4_speciation.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Citric_acid_speciation.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Carboxylic_acid_dimers.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Acetic_acid_pK_dioxane_water.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Chloroacetic_pka.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Fumaric-acid-2D-skeletal.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Maleic-acid-2D-skeletal-A.svg|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Proton_sponge.svg|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">File:Oxalic_acid_titration_grid.png|Acid dissociation constant</ins></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"></gallery></ins></div></td></tr>
</table>
Prab
https://wikimd.org/index.php?title=Acid_dissociation_constant&diff=6288803&oldid=prev
Prab: CSV import
2025-02-11T21:21:01Z
<p>CSV import</p>
<p><b>New page</b></p><div>== Acid Dissociation Constant ==<br />
<br />
The '''acid dissociation constant''', denoted as ''K<sub>a</sub>'', is a quantitative measure of the strength of an [[acid]] in solution. It is the equilibrium constant for a chemical reaction known as dissociation in the context of acid-base reactions. The equilibrium is represented as:<br />
<br />
: HA _ H<sup>+</sup> + A<sup>-</sup><br />
<br />
where HA is a generic acid that dissociates into a proton (H<sup>+</sup>) and its conjugate base (A<sup>-</sup>). The larger the value of ''K<sub>a</sub>'', the more the acid dissociates, and the stronger the acid.<br />
<br />
== Definition and Expression ==<br />
<br />
The acid dissociation constant is defined by the equation:<br />
<br />
: ''K<sub>a</sub>'' = \( \frac{[\text{H}^+][\text{A}^-]}{[\text{HA}]} \)<br />
<br />
where [H<sup>+</sup>], [A<sup>-</sup>], and [HA] are the molar concentrations of the hydrogen ion, the conjugate base, and the undissociated acid, respectively.<br />
<br />
== pK<sub>a</sub> ==<br />
<br />
The ''pK<sub>a</sub>'' is the negative logarithm (base 10) of the acid dissociation constant:<br />
<br />
: ''pK<sub>a</sub>'' = -log<sub>10</sub>''K<sub>a</sub>''<br />
<br />
A lower ''pK<sub>a</sub>'' value indicates a stronger acid, which means it more fully dissociates in solution.<br />
<br />
== Factors Affecting Acid Strength ==<br />
<br />
Several factors influence the strength of an acid, including:<br />
<br />
* '''Electronegativity''': More electronegative atoms can stabilize the negative charge on the conjugate base, increasing acid strength.<br />
* '''Resonance''': Delocalization of charge through resonance can stabilize the conjugate base.<br />
* '''Inductive Effect''': Electron-withdrawing groups can stabilize the conjugate base through the inductive effect.<br />
* '''Hybridization''': The s-character of the hybrid orbitals can affect acidity; more s-character can lead to stronger acids.<br />
<br />
== Examples of Acid Dissociation Constants ==<br />
<br />
=== Acetic Acid ===<br />
[[File:Acetic-acid-dissociation-3D-balls.png|thumb|Acetic acid dissociation]]<br />
<br />
Acetic acid (CH<sub>3</sub>COOH) is a weak acid with a ''pK<sub>a</sub>'' of approximately 4.76. It partially dissociates in water to form acetate ions (CH<sub>3</sub>COO<sup>-</sup>) and hydrogen ions (H<sup>+</sup>).<br />
<br />
=== Phosphoric Acid ===<br />
[[File:H3PO4_speciation.png|thumb|Phosphoric acid speciation]]<br />
<br />
Phosphoric acid (H<sub>3</sub>PO<sub>4</sub>) is a triprotic acid with three dissociation constants, corresponding to the loss of each proton.<br />
<br />
=== Citric Acid ===<br />
[[File:Citric_acid_speciation.png|thumb|Citric acid speciation]]<br />
<br />
Citric acid (C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>) is a weak organic acid with three carboxyl groups, each with its own dissociation constant.<br />
<br />
== Related Concepts ==<br />
<br />
* [[Base dissociation constant]]<br />
* [[pH]]<br />
* [[Buffer solution]]<br />
* [[Titration]]<br />
<br />
== Related Pages ==<br />
<br />
* [[Acid-base reaction]]<br />
* [[Chemical equilibrium]]<br />
* [[Le Chatelier's principle]]<br />
<br />
== Gallery ==<br />
<gallery><br />
File:PK_acetic_acid.png|pK<sub>a</sub> of acetic acid<br />
File:Weak_acid_speciation.svg|Weak acid speciation<br />
File:Carboxylic_acid_dimers.png|Carboxylic acid dimers<br />
File:Acetic_acid_pK_dioxane_water.png|Acetic acid pK<sub>a</sub> in dioxane-water<br />
File:Chloroacetic_pka.png|Chloroacetic acid pK<sub>a</sub><br />
File:Fumaric-acid-2D-skeletal.png|Fumaric acid structure<br />
File:Maleic-acid-2D-skeletal-A.svg|Maleic acid structure<br />
File:Proton_sponge.svg|Proton sponge<br />
</gallery><br />
<br />
[[Category:Acid-base chemistry]]</div>
Prab