ChemistryWiki | RecentChanges | Preferences
Showing revision 7
pH Scale
From the handout on pH scale (given during class) or from the website listed below, pH indicates the relative concentration of the hydronium ion ([H+] or [H3O+]). It is not the concentration of the acid molecule, [HA]. Since strong acids and weak acids ionize to different extent, you need to handle them different with respect to pH calculations.
pH with strong acids
Since strong acid ionize 100%, you can use stoichiometry to figure out the hydronium ion concentration ([H+] or [H3O+]). Once you find the hydronium ion concentration, you can use the pH equation given in the other handout or website below to determine the pH of the solution.
Example:What is the pH of a 0.025M HCl solution.
As with all stoichiometry problem, you must writedown chemical reaction, <br>
1 HCl + 1 H<sub>2</sub>O --> 1 H<sub>3</sub>O<sup>+</sup> + Cl<sup>1-</sup><br>
So (0.025M <nowiki>HCl)(1mole H3O+ / 1 mole HCl) = 0.025M H3O+