begin mathsize 48px style p H space equals space log left square bracket O H to the power of minus right square bracket space plus 14 space end style

 [OH-] = Concentration of OH; pH = -log[H+] ; [H+]= Hydrogen Ion Concentration

 
 

pH

[OH-]

 
Similar to that of strong acids, strong bases are 100% dissociated in water. Thus essentially the concentration of the [OH-] is equal to the base concentration (if the solution is not extreemly dilute). However, when base concentration is very low, we must also consider the OH- ions that are liberated from water. We know that OH- ion concentration exclusively from water is 10-7 mol/L at 25oC. In such situations, we add this quantity to the concentration of base, i.e , for dilute system pOH = -log( C + 10-7) . However when concentration is high, we can omit this contribution of water. The above calculator works well for dilute as well as concetrated strong base solution. It must be noted that when strong bases contain 2 OH - ions (i.e Ca(OH)2 ) the concentration of [OH-] will be 2x(Concentration of the Base). Examples of strong bases include NaOH, Ca(OH)2 etc.

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