Chemistry: Post your doubts here!

[smartangel]

bt doesnt cl from covalent bond between Cl-Cl n vanderwalls force between Cl2-Cl2 like idoine does???

umm i dont understand. what exactly are you trying to say?

 

[xxfarhaxx]

umm i dont understand. what exactly are you trying to say?

isnt the bond between Cl-Cl covalent???
n da bond between Cl2-Cl2 vanderwalls????

 

[Nibz]

Assalamoalaikum wr wb!

got some doubts:

Q2. B because ionisation energy decreses. More shielding effect. Hence, easier to remove the outermost electron.

Q.6 D is correct because. In CrO2Cl2 the o.s of Cr is x -4 -2 = 0 so, x = +6 and in Cr2O3 it's o.s is 2x -6 = 0 , x = + 3
Oxidation state from +6 to +3 is reduction.

Q12. SiCl4 + 2H20 -> SiO2 + 4HCl (normal reaction which is in syllabus of Period 3 elements)
SiO2 is white solid (so white ppt) and HCl is acidic so acidic solution.

Q13. P4O10 + Water -> Phosphoric Acid so acidic pH
PCl5 + Water -> Phosphoric acid + Fumes of HCl so acidic pH. Same effect on pH of P.

Q16. ONLY and ONLY TEMPERATURE AFFECTS THE equilibrium constant Kc. Write this somewhere.

Q24. Intermediate is a Carbocation which has a positive charge. Positive charge means electron lover. Electron lover means electrophile.

Q34.
No possibility at all of Sulfuric Acid formation.
Ammonium sulfate + lime water -> Calcium Sulfate + Ammonia

Q15. Magnesium hyddroxide is a base. NH4+ when donates a proton can act as an acid and so option D is correct.

Q31. Net dipole moment at the NH2 groups may become zero at some point when another hydrogen bond is formed between them and so temporary induced dipole arises. Not sure though.

 

[saudha]

PV = nRT
V = nRT/PV

Moles of water used = Mass/Mr = 1/18 = 0.056...

V (in cm^3) = (0.056 * 8.314 * 596) / (101 x 10^3)
V = 2.72 dm^3

So C is right. It's off by a little but the only option close to it is C. Also, remember that you have to use SI units in the formula.

thank you

 

[Scafalon40]

aoa wr wb!
in that case, you definitely would have received a warning...
Did you?

So you removed that post?
Man I could've sworn it would have been somebody like Nibz!
So did you like that joke
By the way, why did you remove it? You could've just locked it.

 

[Nibz]

So you removed that post?
Man I could've sworn it would have been somebody like Nibz!

Bugger off, man. Don't spoil the flow.

 

[smartangel]

isnt the bond between Cl-Cl covalent???
n da bond between Cl2-Cl2 vanderwalls????

im not sure but how is this related to my question.. do you knw how to answer that one?

 

[XPFMember]

So you removed that post?
Man I could've sworn it would have been somebody like Nibz!
So did you like that joke
By the way, why did you remove it? You could've just locked it.

That's the reason...remember never to suspect someone until you have a proof

When you could joke, then I can act smart enough to remove that thread completely

anyway better not go off-topic.

 

[alphabravocharlie]

Q12. SiCl4 + 2H20 -> SiO2 + 4HCl (normal reaction which is in syllabus of Period 3 elements)
SiO2 is white solid (so white ppt) and HCl is acidic so acidic solution.

Hmh i thought you got Si[oh]4 when you dissolved SiCl4 in water

 

[Nibz]

Yes, sorry. My bad! Wrote that in a hurry. There were too many questions and very little time. The answer still stays the same because the important point is the dissolution of HCl in water

 

[XPFMember]

Hmh i thought you got Si[oh]4 when you dissolved SiCl4 in water

Yes, sorry. My bad! Wrote that in a hurry. There were too many questions and very little time. The answer still stays the same because the important point is the dissolution of HCl in water

chemguide says
These are also called silicon(IV) chloride, germanium(IV) chloride and tin(IV) chloride.
Silicon tetrachloride reacts violently with water to give white solid silicon dioxide and steamy fumes of HCl.

 

[Nibz]

NO, I WAS RIGHT. YOU CONFUSED ME, ALPHA

 

[smzimran]

chemguide says
These are also called silicon(IV) chloride, germanium(IV) chloride and tin(IV) chloride.
Silicon tetrachloride reacts violently with water to give white solid silicon dioxide and steamy fumes of HCl.

AoA
Where do i get chemguide frm?
and other subbjects too?

 

[XPFMember]

NO, I WAS RIGHT. YOU CONFUSED ME, ALPHA

calm down...it's ok ...!!!!
i remember, in the intermediate step, Si(OH)4 is formed!
but in the final step SiO2 is formed....

 

[Nibz]

AoA
Where do i get chemguide frm?
and other subbjects too?

It's a site, dude. Here: http://www.chemguide.co.uk/

 

[XPFMember]

AoA
Where do i get chemguide frm?
and other subbjects too?

Waalaikumassalam wr wb!

chemguide...i was talking about the website..
http://www.chemguide.co.uk/CIE/section93/learningc.html#top

 

[XPFMember]

It's a site, dude. Here: http://www.chemguide.co.uk/

You hadn't made the post when I clicked reply..

 

[smzimran]

Waalaikumassalam wr wb!

It's a site, dude. Here: http://www.chemguide.co.uk/

chemguide...i was talking about the website..
http://www.chemguide.co.uk/CIE/section93/learningc.html#top

Oh, sorry...
Btw, Is there any revision guide or revision checklist published by CIE ?

 

[Nibz]

Oh, sorry...
Btw, Is there any revision guide or revision checklist published by CIE ?

Check here: http://www.cambridgestudents.org.uk/subjectpages

 

[smartangel]

7 Which pair of elements have bonds of the same type between their atoms in the solid state?
A aluminium and phosphorus
B chlorine and argon
C magnesium and silicon
D sulphur and chlorine

why is the answer D and not A or B?