About us | Feedback

Discussion of the equation for salt pH calculation

pH calculation

pH questions

BATE pH calculator

operating systems:
XP, Vista, 7, 8, 10

single user license price:
€24.95 - approximately $33

Buy Now!

By clicking Buy Now! you will continue to the FastSpring checkout page where payment will be taken, and your order fulfilled by FastSpring, our trusted reseller, and Merchant of Record.

download 30-day free trial!
30-day money back guarantee!

pH calculation lectures » more on the salt pH calculation

Equation 11.13 derived in salts in general section is one of the most interesting and universal we have seen to this time. Almost all problems solved before are just its particular cases.

eq. 14.114.1

In the case of mixture of strong acid and strong base both dissociations constants are large and we can assume Ka>>[H+], Kb[H+]>>Kw. That means that in both sums in denominators smaller values can be neglected. After canceling out what we are left with is

eq. 14.214.2

which is a more universal form of equations 7.4 and 7.7 - this time it describes solution containing both strong acid and base, regardless of their concentrations. Even for diluted solutions results will be correct, as water dissociation is taken into account thanks to Kw presence. Putting Ca=0 or Cb=0 we are getting quadratic equations for pH of strong base or acid.

In case of solution of salt of strong acid and strong base Ca=Cb and these cancel out, leaving the simplest possible thing:

eq. 14.314.3

We can also put Cb=0 to get

eq. 14.414.4

which is nothing else but equation 6.8 describing pH of any acid solution.


Chemical calculator software for pH calculation, concentration conversion solution preparation and chemical equation balancing chemical calculator