This is a relatively easy question. First, you should have your chemical equation.
HA + h20 <---> A^1- + H30^1+
Basically Ka is our ionization constant. The simple formula for this is Products / Reactants. Water is excluded because it doesnt contribute to the Ka although it acts as a Bronsted-Lowry Base on the left side of the equation.
So the Ka of a weak acid should be : Ka = [H30^1+] X [A^1-] / [HA]
A^- is the conjugate base of the weak acid.
If they give u Kb value its even easier.
You should have learned that Kw = [Ka] x [Kb]
Kw at 25 degrees celsius should always be 1.00 x 10^-14.
So if they give you kb....
Ka = 1.00 x 10^-14 / Kb value.
I hope this helped!
Galvin H
a weak acid has a larger ka value, while a strong acid has a small ka value
A weak acid has a pKa value in the approximate range −2 to 12 in water.
Strong acids have their acid dissociation constants in the order of 10 to the power 7 or more. Hence, it is difficult to find it using a titration process.
Assuming you know how to find the equivalence point on the titration curve, and assuming it is not [strong acid/strong base] or [weak acid/weak base], all you need to do is find the half equivalence point, which gives you the pKa of the first solution. Then to get the Ka, you go 10-pKa .
It is the nearly horizontal region before the equivalence point.
conductometric titration of a strong acid with a strong base makes the sloution neutral
Answering "http://wiki.answers.com/Q/Why_the_titration_curve_is_varying_with_different_acid_base_titration"
This is so because titration of a weak acid with a weak base do not give a sharp change inconductivity curve. Hence it is not possible to determine the end point from the curve.
Assuming you know how to find the equivalence point on the titration curve, and assuming it is not [strong acid/strong base] or [weak acid/weak base], all you need to do is find the half equivalence point, which gives you the pKa of the first solution. Then to get the Ka, you go 10-pKa .
It is the nearly horizontal region before the equivalence point.
conductometric titration of a strong acid with a strong base makes the sloution neutral
The pka of oxalic acid can be determined with the help of titration curve. The slight inflection that occurs corresponds to the first end point.
Answering "http://wiki.answers.com/Q/Why_the_titration_curve_is_varying_with_different_acid_base_titration"
Answering "http://wiki.answers.com/Q/Why_the_titration_curve_is_varying_with_different_acid_base_titration"
This is so because titration of a weak acid with a weak base do not give a sharp change inconductivity curve. Hence it is not possible to determine the end point from the curve.
by weight
It is difficult to determine the end point of such a titration, because the titration produces a buffer solution that changes its pH very slowly at the end point, in contrast to reaction between a strong acid and strong base.
they form nutral solution
Phenolphtalein is an indicator used to find the endpoint of a reaction (specifically an acid-base reaction). It has a pH range of 8.3 to 10.0 which means it can be used for a strong acid to strong base titration or a weak base to strong acid titration. Phenolphthalein is clear when it is in the presence of acid and pink when it is in the presence of a base.
a strong acid and a weak base.