CO2 vs. H2O

(Polar molecules, Non-polar molecules, etc.)

Moderators: Chem_Mod, Chem_Admin

Elizabeth Ignacio 1C
Posts: 39
Joined: Fri Sep 29, 2017 7:07 am

CO2 vs. H2O

Postby Elizabeth Ignacio 1C » Mon Nov 13, 2017 6:57 pm

Hi! What exactly makes carbon dioxide non-polar while H2O is polar? I know that it has to do with its dipole moments, but I'm unsure how you can look at the dipole moments and determine polarity. Thanks!

Angel Ni 2K
Posts: 50
Joined: Sat Jul 22, 2017 3:01 am

Re: CO2 vs. H2O

Postby Angel Ni 2K » Mon Nov 13, 2017 7:38 pm

1. Draw VSEPR structures.
2. Draw dipole moments.
3. CO2 has dipole moments, but they cancel out because they are equal in magnitude and opposite in direction. Therefore, CO2 is a nonpolar molecule despite having polar bonds. H2O has dipole moments, but they do not cancel out because they are equal but not opposite in direction. Therefore, H2O is a polar molecule and has polar bonds.

Ramya Natarajan 1D
Posts: 24
Joined: Fri Sep 29, 2017 7:04 am

Re: CO2 vs. H2O

Postby Ramya Natarajan 1D » Mon Nov 13, 2017 11:11 pm

Keep in mind that in CO2, Oxygen is more electronegative, so the dipole moments are facing opposite directions (away from the central atom of Carbon), making the molecule polar. In H2O, Oxygen is more electronegative, so the dipole moments would face inwards towards oxygen and consequently cancel out. Another thing to keep in mind is thinking of dipole moments as vectors--equal but opposite directions would cancel each other out.

Alexandria Weinberger
Posts: 51
Joined: Fri Sep 29, 2017 7:03 am

Re: CO2 vs. H2O

Postby Alexandria Weinberger » Tue Nov 14, 2017 12:44 pm

In CO2 the dipole moments cancel out, while in H2O, they don't, making it polar.

Pooja Nair 1C
Posts: 55
Joined: Thu Jul 13, 2017 3:00 am

Re: CO2 vs. H2O

Postby Pooja Nair 1C » Tue Nov 14, 2017 1:33 pm

In CO2, both oxygens are more electronegative than the carbon, but they pull equally apart from one another, so there is no dipole moment (the pulls cancel). Meanwhile, in H2O, oxygen has two lone pairs as well as the bonds to the hydrogen, so the electrons are concentrated on oxygen and are not canceled out by anything, therefore it has a dipole moment and is polar.

mayasinha1B
Posts: 70
Joined: Fri Sep 29, 2017 7:04 am

Re: CO2 vs. H2O

Postby mayasinha1B » Tue Nov 14, 2017 3:17 pm

h20 is not linear, and it's dipole moments do not cancel. If you draw dipole moments on co2 then you see that they cancel out, making co2 nonpolar.

Adrian Lim 1G
Posts: 88
Joined: Fri Sep 29, 2017 7:03 am

Re: CO2 vs. H2O

Postby Adrian Lim 1G » Tue Nov 14, 2017 6:39 pm

H20 has a bent structure, so the dipole moments that move towards the more electronegative oxygen do not cancel out, making H20 polar. However, in CO2, the structure is linear, meaning the dipole moments would end up cancelling out each other, making it non polar.


Return to “Determining Molecular Shape (VSEPR)”

Who is online

Users browsing this forum: No registered users and 2 guests