top score gen chem help?

[bittersweet008x]

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when 14.250 moles of PCl5 gas is placed in a 3.00 L container @ equilibrium @ constant Temperature, 40% of PCl5 decomposes

PCl5(g) --><--- PCl3(g) + Cl2(g)

What is Kc?

-- for some reason I am having a hard time setting up this problem, I know how to find the molarity but then when I am setting up Kc= prod/react .. i think i might be doing it wrong? & I can seem to figure out what #'s plug in where? if that makes sense?

-- top score explanation wasn't too great, so Id LOVED some help 🙂

 

[mmoosavi41]

molarity times .4 will give you the value of the concentration for PCl3 and Cl2. so you have that number squared on top. now since 40% decomposes, 60% is still left. so you multiply your molarity by .6 and that will be the concentration of PCl5. i'm not the best at explaining something like this conceptually but i hope this helps.

if i'm not mistaken, the final answer should be something like (1.89)^2/2.88 or something like that.

 

[casper22]

+1

 

[bittersweet008x]

yesss! that completely makes sense now!

thank you so much!

 

[mmoosavi41]

yesss! that completely makes sense now!

thank you so much!

yup, no problem. glad i can help.