gen chem question.

[savvysearch]

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please help. Thanks.

when 14.250 moles of PCl5 gas is placed in 3 L container and comes to equilibrum at constant temp. 40% of PCl5 decomposes according to:

PCl5 --><-- PCl3 +Cl2

what is Kc value?

Answer: (1.862)(1.862)/2.854

why?


what is the net ionic equation?
HCl+NaOH -->H20 + NaCl

answer:
H30+(aq)+0H-(aq)-->2H20 (l)

why?

 

[briansle]

Make and ICE table to solve this, then it will be clear

PCl5 --><-- PCl3 +Cl2
Initial: 4.75M 0M 0M
Change: -x x x
Equilbri: 4.75-x x x
2.854 1.896 1.896

Since the problem says that 40% of PCl5 is used up, then 60% is remaining at equilibrium so that is where you get 2.854M. 14.25mol/3L x 60%= 2.854M
Knowing this one equilibrium factor, you make the ICE table and solve for the X variable, which in this case is conveniently what the two products are.

Do some more equilibrium problems, the more you do, the easier it'll get.

Sounds like you got finals coming up next week or something, man if you don't know this yet, I'd be scared. But have no fear. Here's the trick to getting A's in all of your college classes:
Sit next to an Asian Kid If he give starts complaining about you, just smack his face and set him straight. Worked for me, it'll work for you. Oh by the way, it works better if your black or hispanic.

For that net ionic one, I think its just H20 because you exclude anything insoluble like salt(NaCl) which would form a solid. I'm not sure though, double check.

 

[toothfaerie]

Na and Cl form precipitate .

Hydronium ion and OH remain soluble . The net ionic eqn discounts whatever precipitates out.

TF

 

[aphistis]

Na and Cl precipitate out?

You've never dissolved table salt in water?

 

[toothfaerie]

🙄 never mind...

 

[savvysearch]

thanks! can someone answer the second one?

 

[critterbug]

Well, depends if the solution is saturated or not.


NaCl can precipitate out of a super-saturated sol'n


But this has no relevance to the original problem posted.