Chemistry: Post your doubts here!

[angelicsuccubus]

What kinds of compounds vapourise at low temperatures?

 

[angelicsuccubus]

and.. how come aluminium chloride is covalent but aluminium fluoride is ionic?
what's the metal used as a catalyst in a vehicle's catalytic converter? (palladium.. platinum..? can't remember)

 

[ibadsiddiqi]

and.. how come aluminium chloride is covalent but aluminium fluoride is ionic?

The aluminium ion is very small and is pack with 3+ charges-the charge density is therefore very high. so the electrons are dragged over to the aluminium ion. However since the chlorine is more electronegative than aluminium, it pulls the electrons towards itself such that the bond formed is polar.
However in the case of aluminium flouride, flourine is much more electronegative than aluminium and so it drags the electrons towards itself. Aluminium has lost control over its electrons and flourine has gained control. Hence aluminium flouride is ionic
I can explain this more fully if u want me to

 

[ibadsiddiqi]

What kinds of compounds vapourise at low temperatures?

That would be covalent compounds

 

[Soulgamer]

and.. how come aluminium chloride is covalent but aluminium fluoride is ionic?
what's the metal used as a catalyst in a vehicle's catalytic converter? (palladium.. platinum..? can't remember)

^the guy answered it correct.
Palladium and platinum both are used in catalytic converters.

 

[Soulgamer]

What kinds of compounds vapourise at low temperatures?

You must be talking about Volatility. The weaker the inter-molecular forces are, the more volatile the compound is. Alkanes are generally volatile. This came in an MCQ.

 

[ibadsiddiqi]

You must be talking about Volatility. The weaker the inter-molecular forces are, the more volatile the compound is. Alkanes are generally volatile. This came in an MCQ.

yea but thats going to come under covalent compounds right?

 

[Soulgamer]

yea but thats going to come under covalent compounds right?

Strictly speaking, yes. As covalent compounds have weak inter-molecular forces. Always relate volatility with weak inter-molecular forces.

 

[prannoy]

Structural formula of 3 esters from c5h10O2?

 

[angelicsuccubus]

The aluminium ion is very small and is pack with 3+ charges-the charge density is therefore very high. so the electrons are dragged over to the aluminium ion. However since the chlorine is more electronegative than aluminium, it pulls the electrons towards itself such that the bond formed is polar.
However in the case of aluminium flouride, flourine is much more electronegative than aluminium and so it drags the electrons towards itself. Aluminium has lost control over its electrons and flourine has gained control. Hence aluminium flouride is ionic
I can explain this more fully if u want me to

hmm I think I get it .. so basically Al and Cl end up sharing the electrons but Al and F can't cause F took them almost competely?

 

[angelicsuccubus]

You must be talking about Volatility. The weaker the inter-molecular forces are, the more volatile the compound is. Alkanes are generally volatile. This came in an MCQ.

nah I just saw a question in the specimen paper of 2000 or 2001 about aluminium chloride and it's vapour state

 

[arkif rizan]

y is 1st IE of Mg is greater than 1st IE of Al? and wat is orbital overlap??

 

[ibadsiddiqi]

hmm I think I get it .. so basically Al and Cl end up sharing the electrons but Al and F can't cause F took them almost competely?

Yes thats right. Chlorine is not electronegative enough to pull the electrons all the way to itself because of the high charge density of aluminium but fllourine is capable. so yea F takes them completely.

 

[aaditya menon]

y is 1st IE of Mg is greater than 1st IE of Al? and wat is orbital overlap??

Mg : 1s2 2s2 2p6 3s2

Al : 1s2 2s2 2p6 3s2 3p1

It is easier to remove the 3p1 electron from Al, more shielding, repulsion from inner electrons and greater distance from nucleus.

Well, to understand orbital overlap, you should understand the concept of hybridization. As a summary, orbital overlap occurs
when s or p orbitals overlap with each other to form hybrids. For instance, in methane, sp3 hybridization occurs.

 

[ibadsiddiqi]

y is 1st IE of Mg is greater than 1st IE of Al? and wat is orbital overlap??

In Mg the outermost electron is in 3S while in Al it is in 3P. 3P is further away from the nucleus hence the ionization energy of Mg is higher

 

[arkif rizan]

thnk u

 

[angelicsuccubus]

Yes thats right. Chlorine is not electronegative enough to pull the electrons all the way to itself because of the high charge density of aluminium but fllourine is capable. so yea F takes them completely.

ty =]

 

[Casablanca]

Okay, this is pretty simple, but it's not stated clearly in my book, so I'll ask here.

Can someone please name the kinds of intermolecular forces in order of strength? I know that Hydrogen bonds are strong, and Van der Waals are weak, but just need confirmation. Also, are dipole-dipole forces and Ionic bonds the same thing?

 

[smzimran]

Okay, this is pretty simple, but it's not stated clearly in my book, so I'll ask here.

Can someone please name the kinds of intermolecular forces in order of strength? I know that Hydrogen bonds are strong, and Van der Waals are weak, but just need confirmation. Also, are dipole-dipole forces and Ionic bonds the same thing?

Ionic bond >> H.B > Van der Waal's

No they are different!

 

[ibadsiddiqi]

Okay, this is pretty simple, but it's not stated clearly in my book, so I'll ask here.

Can someone please name the kinds of intermolecular forces in order of strength? I know that Hydrogen bonds are strong, and Van der Waals are weak, but just need confirmation. Also, are dipole-dipole forces and Ionic bonds the same thing?

sure..in increasing order of strength: Temporary dipole-dipole interactions(more commonly known as the dispersion forces), dipole-dipole interaction and the strongest hydrogen bonding.
No dipole-dipole forces are 1 of the van der waals forces, completely different thatn Ionic bonds. You want me to explain dipole-dipole interactions?