Specific Notation

[NatBrown1I]

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

[Kristen Kim 2K]

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.

[2c_britneyly]

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.

[Sarah Fatkin 4I]

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!

[Mya Majewski 1L]

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

[Vicky Lu 1L]

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).