Why is there PCl5

authormessagesastleitner
 Post subject: Re: Exam questions 5.2.2011
  Posted: 02.03.2011, 14:06 
Stem cell researcher

Registered: 28.09.2009, 20:48
Posts: 684
1) Without octet rule: Looks like a sun, Te can form 6 bonds -> therefore 6 * SH. As far as I can see, there are no mes either. Structures.
I don't see how to draw this molecule WITH OR. > _>

2) If the normal potential is> 0 (i.e. positive), this means that the respective metal is less noble than hydrogen (normal potential 0), i.e. it goes into solution. The other metals are more noble and will be preserved.

No guarantee.

Kind regards


 Dan
 Post subject: Re: Exam questions 5.2.2011
  Posted: 02.03.2011, 15:38 
Guinea pigs

Registered: 15.11.2010, 10:08
Posts: 1
RE 2) I would say if the substance has a positive NP then it is more noble than hydrogen


 tomatoe
 Post subject: Re: Exam questions 5.2.2011
  Posted: 04.03.2011, 14:23 
Guinea pigs

Registered: 22.08.2010, 22:14
Posts: 24
Question about group A -c

There are PCl5, PCl3 and NCl3, but not NCl5, right?
and do PCl3 and NCl3 have a double bond, or does it just look like that?

Cl - N - Cl or Cl - P - Cl
l l
Cl Cl


 ChaoTic
 Post subject: Re: Exam questions 5.2.2011
  Posted: 04.03.2011, 17:42 
Labor junky

Registered: 30.11.2008, 17:45
Posts: 561
Wibelmeister wrote:
That was the pH value for example of group A.

An NH3 solution (c = 0.5) is added dropwise to 1L NH4Cl (c = 0.1) until it has a pH value of 9.7.
Calculate the V of the added NH3 solution.
N = 14 H = 1 Cl = 35.5
KB (NH3) = 1.8 * 10 ^ -5

Can anyone solve the vl?


that would be the same example as in the mortimer on page 305. where the example was given with aniline. but there it asks about the pH, which doesn't matter. there you can also see why they gave the relative atomic masses and what to do with them. similar ones are also in chapter 19. one does not get to the result by inserting into the formula c1 * V1 = c2 * V2


 ChaoTic
 Post subject: Re: Exam questions 5.2.2011
  Posted: 04.03.2011, 18:02 
Labor junky

Registered: 30.11.2008, 17:45
Posts: 561
Question about group A -c

There are PCl5, PCl3 and NCl3, but not NCl5, right?
and do PCl3 and NCl3 have a double bond, or does it just look like that?

Cl - N - Cl or Cl - P - Cl
l l
Cl Cl



NCl5 does not exist because N is in the 2nd period where the octet rule applies. and N is only allowed to enter into 4 bonds, but here 5 Cl are bound to the N, which cannot be.

The octet rule does not apply to PCl3 because you are in the 3rd period. ie. P can form a maximum of 5 bonds and Cl 7 (depends on the external electrons).
in that case you can draw it like this:

Cl = P = Cl
l
Cl

With NCl3 you use the formula to calculate how many bonds it can enter into, because of the octet rule there are only 3, which is why it has no double bonds here.

lg