help!

[davedefunk]

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Hey guys can you please help me out with this checm problem....they are asking for K (c).....im not even sure wat that stands for........any help or guidance is appreciated!


when 14.250 moles of PCL5 gas is placed in 3.0 liters container and comes to equi at a constant temp, 40% of the PCL5 decomposes acording to the equation:

PCL5 (g) -> PCL3 (g) + CLs (g)

what isthe value of K(c) for this reaction?

answer-- (1.896)^2 / 2.854

 

[Jo23]

Kc=equilibrium constant
Kc=[PCl3]x[Cl2]/[PCl5]

[substance x]=nr of moles of substance x/volume in liters

You have the volume, so you need to find the nr of moles of reactant and products.

It says that 40% of PCl5 is decomposed-> 40%x14.250=5.7 mols PCl5 are decomposed-> 14.250-5.7=8.55 mols PCl5 are left

So, [PCl5]=8.55 mols/3.0 l=2.85

From the reaction, you can easily see that if 5.7 mols of PCl5 are decomposed, then 5.7 mols of each products will be formed.

So, [PCl3]=[Cl2]=5.7mols/3.0 liters=1.9

Going back to the equation, Kc=1.9x1.9/2.85

I hope it helps.

 

[davedefunk]

thanks a lot bro.....this really helps😀