Which of these molecules are polar (there are many answers)

MgF2
NF3
CF4
PF3
BF3
BeH2
BH3
CH4
NH3
H2O
CCl4
CHCl3
CH2Cl2
CH3Cl
CH4

and which molecules are sp2 hybridized? (there are many answers)

HCN
H2CO
C2F2
PH3
HNC
CH4
H2CO
C2F2
BH3
NH3
BF3
H2CO
CH3F
PH3
NH3

First part the following are polar: MgF2 -- NF3 -- PF3 -- NH3 -- H2O -- CHCl3 -- CH2Cl2 -- CH3Cl

Second part just find any of those molecules with double bonds to Carbon and if they have at least one double to Carbon then they are sp2 hybridized for that carbon.

Edit: If you need further help just pm i'll be glad to help you.

This post was edited by Kamel on Oct 21 2011 06:25pm

wtf?
chcl3, ch2cl2 are not polar, at all. I Don't think Ch3Cl is polar either. You use them in oragnic chemistry to extract non-polar analytes. don't listen to the above post.
NF3, PF3, NH3, H2O are definitely polar.

I Don't think MgF2 is polar either - it is a salt, and ionizes in h2o.

2. sp2
H2CO,
C2F2
HNC is not really stable, but it would be sp2 (if you don't actually mean HCN, HCN is not sp2, it is sp1)
You have HJ2CO here twice, and C2F2... now you have H2CO three times.

you can have sp2 in atoms other than carbon, as well...

Sp2 hybridized carbons have 3 atoms or lone pairs bonded to them.

NH3 is not sp2 hybridized, because its bonded to 3 atoms + a lone pair, making it Sp3.

BF3 is Sp2 hybridized because its one of those few atoms without a lone pair, but is happy with just 3 atoms bonded to it.

And for a molecule to be polar, it has to have a dipole. This means that one side or sides of the atom need to be positive, and the other(s) need to be negative in charge based on atom electronegativity + lone pairs of electrons

This post was edited by RUSSiABANK on Oct 22 2011 11:18am

draw lewis dot structure for each. Polar molecules includes electronegative substituants, and are asymmetric. ie. halide groups+ bent/trigonal pyramidal
as to greendischarge's post, CHCl3, CHCL2, CHCL are definitely polar (CCl4 is not polar because it is tetrahedral = symmetry), . You use them to extract non-polar solutes because non-polar solutes do not dissolve in polar solvents.

as for sp2. Add up the number of sigma bonds and lone pairs of electron, this give you the steric number. sp2 has a steric number of 3. Note that if a lone pair is involved in resonance/localization, it's not counted (don't know if you need to know this much)

Probably something wrong in your brain.

Just went over this with someone else.

Everything exhibits some kind of polarity - even methane.

However, things with <5 in their polarity index are generally considered non polar. There is no absolute objective "point" where things become polar or non-polar.

CHCl3 is technically non-polar, however it exhibits polarity. It is not miscible in water, but miscible with hexane.

An organic chemist will agree with this:
chcl3, ch2cl2 are not polar, at all. I Don't think Ch3Cl is polar either.

A physical chemist may differ in response.

And in general chemistry you usually take a physical chemistry approach.

No.No.No.
All chemists will agree that CHCl3, CH2Cl2, CH3Cl are polar.
However, all chemistry will also agree that none are miscible in water. They are not miscible in water because they do not form hydrogen bonds and cannot dissociate in water. Just because something is polar does not mean it is miscible in water. They must be able to form hydrogen bonds in water (or dissociate in water).

I think you are confusing "polarity" and "miscibility". because in practical approach, no chemists talk about polarity, they only care if molecules are miscible or not.

and btw, physical and organic chemistry are two different fields. The fundamental theories of chemistry remains the same for both sides, responses for such simple questions will be the same.

This post was edited by Exx on Oct 22 2011 02:20pm