### Ka*Kb=Kw

Posted:

**Tue Jan 21, 2020 11:46 am**For the Ka*Kb=Kw equation, does it make a difference if we say Kw=10^-4 or 1.0*10^-4?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=59&t=56921

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Posted: **Tue Jan 21, 2020 11:46 am**

For the Ka*Kb=Kw equation, does it make a difference if we say Kw=10^-4 or 1.0*10^-4?

Posted: **Tue Jan 21, 2020 11:50 am**

It does not make a difference for calculations since 10^-14 and 1.0 x 10^-14 are the same thing but you should note that 1.0 x 10^-14 gives you two sig figs which would be useful to have the correct number of sig figs in your answer.

Posted: **Sat Jan 25, 2020 12:29 pm**

Make sure you are using -14 not -4!

Posted: **Sat Jan 25, 2020 5:10 pm**

No, in calculation you should get the same thing since 1 times anything is still that value. Just make sure to keep sig. figs. in mind.

Posted: **Sat Jan 25, 2020 5:52 pm**

Kw= 10^-14 and Kw= 1.0 * 10 ^-14 are the same but I believe in the book they used 1.0 * 10 ^-14 because it helps keeping up with the sig figs. But remember that Kw=10 ^-14 ONLY at 25 degrees Celsius.

Posted: **Sat Jan 25, 2020 6:01 pm**

Both mean the same thing so it does not matter which one that you use.