### Specific Notation

Posted:

**Wed Jan 23, 2019 2:09 pm**Does it matter whether or not when you're calculating K to use this notation [PCl5] or this notation P PCl5 ?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=49&t=40565

Page **1** of **1**

Posted: **Wed Jan 23, 2019 2:09 pm**

Does it matter whether or not when you're calculating K to use this notation [PCl5] or this notation P PCl5 ?

Posted: **Wed Jan 23, 2019 2:34 pm**

If PCl5 is aqueous, I would use [PCl5], and if PCl5 is gaseous, use P PCl5. Unless they specify to find partial pressure, I would just use the concentration notation.

Posted: **Wed Jan 23, 2019 2:34 pm**

Yes, if you're dealing with a reaction that involves only gases it is more correct to use P_{gas}, but if you're calculating for a reaction that involves an aqueous solution, you should use hard brackets to indicate K_{c}.

Posted: **Wed Jan 23, 2019 4:15 pm**

You should get the same K value regardless of which notation you use; however, partial pressure is usually used for gases and concentration is usually used for solutions. Hope this helps!

Posted: **Wed Jan 23, 2019 10:23 pm**

pay attention if the problem gives you Kc or Kp, then you know which to use!

Posted: **Thu Jan 24, 2019 12:08 am**

Notation does matter when calculating K. Use brackets when dealing with concentration such as [PCl5]. Brackets are not require if you write out the value of the concentration of PCl5. As for the gaseous states, you don't not use brackets. If you want, you can use parentheses around P PCl5 like so (P PCl5).