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Help in AS Chemistry!

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The SMA:
i need help to answer M/J 2005 paper 2
on Q2 (d iii) ,  Q5 (a) and (c)

and on M/J 2004 paper 2
Q3 c ( the whole question c)

and there's something xtra i wanna ask from u guys,
can someone please explain to me what is permanent dipole, induced dipole
and dipole-dipole interactions?

Will really appreciate if someone could help me :)

unknown 101:

--- Quote from: The SMA on May 21, 2010, 12:14:02 pm ---i need help to answer M/J 2005 paper 2
on Q2 (d iii) ,  Q5 (a) and (c)

and on M/J 2004 paper 2
Q3 c ( the whole question c)

and there's something xtra i wanna ask from u guys,
can someone please explain to me what is permanent dipole, induced dipole
and dipole-dipole interactions?

Will really appreciate if someone could help me :)

--- End quote ---

from the equation in 2)d) (i) u know that 2 mol of H2S reacts with 3 mol of 02
find the mr of H2S  (2 + 32.1 )will give 34.1 multiply by two ( as there are 2 moles ) to get 68.2
and u know that 1 mol = 24dm3 so 3 moles will = 72
so now u have the all the values soo...
if 68.2g of H2S reacts with 72 dm3 of O2
 so 8.65g will react with X
cross multiply ( 8.65 x 72 / 68.2 ) = 9.13 dm3


2nd question:

3)c) (i) u know that 1.20 dm3 of NH3 was dissolved so.....
if         1 mole = 24dm3
then     X mole = 1.2 dm3
cross multiply (1.2/24 = 0.5 mol )

c) (ii) equation: 2NH3 + H2SO4 -----> (NH4)2SO4

c) (iii) if 2 mol of ammonia is required to nuetralize 1 mol of sulphuric acid so....
from part (i) u know that we have 0.05 mol of ammonia, so to nuetralize it we need ( 0.05/ 2 = 0.025)

so now we have the moles and concentration, rearrange the formula ( mol = vol x conc ) to find the volume
so...
vol = mol/ conc ----->  0.025/0.5= 0.05 dm3, and we need the volume in cm3, so multiply by 1000
(0.05 x 1000 = 50cm3) so 50 cm3 is required to nuetralize 200 cm3 of aqueous ammonia


permanent dipole : is when you have a polar molecule with oppositely charged ends, and these ends attract other polar molecules, bonding them together. The polar molecules will always be slightly negative on one end and slightly positive on the other.

induced dipole: A dipole-induced dipole attraction is a weak attraction that results when a polar molecule induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species.

OR SIMPLY: when a non-polar molecule has it's electron density shifted by a charged molecule, i.e., if a positively charged species is brought near a species with an evenly distributed charge, the electrons go towards the side where the positive species is, and away from the opposite side, creating an artificial dipole

dipole-dipole interaction: this is just the weak van der waal's forces of attraction


hope this helped ;)

[Spy]:
thats how we roll nashat ;)

unknown 101:

--- Quote from: Spy on May 21, 2010, 02:15:10 pm ---thats how we roll nashat ;)

--- End quote ---

hahhahaha ;)

The SMA:
Many many thanks unknown 101 for enlightening all my doubts. Reaaaaaly Appreciate it :) :)

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