How can I find the acid dissociation constant of a weak acid without using the half-neutralisation method?
Igloo replies The most straightforward way is to make use of the relationship: Ka = [H+]2 / [HA] in which HA represents the monoprotic (monobasic) acid. A titration with a standard solution of an alkali, using phenolphthalein as indicator, will lead you to the value for [HA], and probably the easiest way to determine [H+] is to use a pH meter, and then subsequently to use the relationship pH = – log10[H+] The pH meter will need to be an accurate one, preferably digital, and it will also need to be carefully calibrated with relevant buffer solutions before use. Always carry out a risk assessment before starting any practical work, and check with your teacher. Risk assessment Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or colleg
