04-07-2018, 03:13 PM

Hi!! ...I don't understand a thing about the approximated formula of the general equation of a strong acid/strong base tritation.

The general expression is:

[H+]- Kw/[H+] = C0D * (1-φ) = C0 * (C/C+φC0) * (1-φ)

Where D= (C/C+φC0) is the diluition factor , C the concentration of the titrant while C0 the titrand one

Now my textbook says that sometimes I can approximate this expression assuming that D≈1 (for all φ values)

Now my question is WHEN I can do this assumption (??). My textbook says when the titrand concentration , C0, is much more concentrated than the titrant one...But in terms of number what does it means?

How much order of magnitude the difference between (C_0 and C) must be??

Thanks a lot,and sorry for my bad english.

The general expression is:

[H+]- Kw/[H+] = C0D * (1-φ) = C0 * (C/C+φC0) * (1-φ)

Where D= (C/C+φC0) is the diluition factor , C the concentration of the titrant while C0 the titrand one

Now my textbook says that sometimes I can approximate this expression assuming that D≈1 (for all φ values)

Now my question is WHEN I can do this assumption (??). My textbook says when the titrand concentration , C0, is much more concentrated than the titrant one...But in terms of number what does it means?

How much order of magnitude the difference between (C_0 and C) must be??

Thanks a lot,and sorry for my bad english.