Both H₂O and CO₂ have polar bonds. Why does water dissolve salt but CO₂ does not?

Water is bent, so its bond dipoles add to a large net dipole (1.86 D displayed), making it an excellent polar solvent. CO₂ is linear with zero net dipole — it is nonpolar.

Predict whether CHCl₃ (chloroform) is polar or nonpolar, and explain why.

CHCl₃ is polar (μ ≈ 1.04 D). It has tetrahedral geometry but the four substituents are not identical — three Cl atoms vs one H — so bond dipoles do not cancel.

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Molecular Polarity

Visualize dipole moments and electron density in 3D

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How it works

Molecular Polarity demonstrates a key principle: A bond is polar when two atoms have different electronegativities — the more electronegative atom pulls electron density toward itself, creating a partial negative charge (δ⁻) and leaving the other end partially positive (δ⁺). A bond is polar when two atoms have different electronegativities — the more electronegative atom pulls electron density toward itself, creating a partial negative charge (δ⁻) and leaving the other end partially positive (δ⁺). Each polar bond has a dipole moment vector pointing from δ⁺ to δ⁻. The net molecular dipole is the vector sum of all bond dipoles. In symmetric molecules like CO₂ or CCl₄, bond dipoles cancel perfectly (net μ = 0, nonpolar). In asymmetric molecules like H₂O or CHCl₃, dipoles add up to a nonzero net moment (polar). Polarity determines solubility, boiling point, and intermolecular forces.

Step-by-step

Select a molecule to view its 3D structure with electron density cloud.
Blue regions show higher electron density (δ⁻), red regions show electron-poor areas (δ⁺).
Bond dipole arrows point from positive to negative.
The net dipole arrow (yellow) shows the overall molecular polarity.
Toggle dipoles and electron cloud on/off.
Rotate the model to see how geometry affects polarity.

Key formulas

$\vec{\mu} = q \times d$ Dipole moment: product of partial charge magnitude and bond distance (units: Debye)
$\vec{\mu}_{\text{net}} = \sum_i \vec{\mu}_i$ Net molecular dipole is the vector sum of all bond dipole moments

Frequently asked questions

Both H₂O and CO₂ have polar bonds. Why does water dissolve salt but CO₂ does not?: Water is bent, so its bond dipoles add to a large net dipole (1.86 D displayed), making it an excellent polar solvent. CO₂ is linear with zero net dipole — it is nonpolar.
Predict whether CHCl₃ (chloroform) is polar or nonpolar, and explain why.: CHCl₃ is polar (μ ≈ 1.04 D). It has tetrahedral geometry but the four substituents are not identical — three Cl atoms vs one H — so bond dipoles do not cancel.