Question

Although both CO2 and H2O are triatomic molecules, the shape of H2O molecule is bent while that of CO2 is linear. Explain this on the basis of dipole moment.

Answer 1

CO2 is nonpolar because its linear shape causes the dipoles to cancel each other out, while H2O is polar due to its bent shape, resulting in a net dipole moment.

Step-by-step explanation:

The difference in shape of CO2 and H2O molecules can be traced back to their electronegativity differences and molecular geometry. CO2 has a linear structure with two polar covalent bonds. The oxygen atoms are more electronegative than the carbon atom, therefore, individual dipoles exist pointing away from carbon to each oxygen. However, these dipoles are of equal strength and are directed in opposite directions, thus canceling each other out, rendering CO2 nonpolar.

In contrast, H2O has a bent molecular structure due to the two lone pairs on the central oxygen atom, which repel the hydrogen atoms. This creates a situation where the individual dipoles do not cancel each other out because they are not directed in opposite directions. Consequently, H2O has a net dipole moment and is classified as a polar molecule.

Answer 2

The difference in the shapes of CO₂ and H₂O molecules can be seen based on the concept of VSEPR (Valence Shell Electron Pair Repulsion) theory and the presence of lone pairs of electrons.

What is the basis of dipole moment?

The difference in molecular shapes between H₂O and CO₂ is said to be one that is attributed to their respective dipole moments. H₂O has a bent shape due to the presence of two lone pairs of electrons on the central oxygen atom, causing electron-electron repulsion and pushing the hydrogen atoms into a bent configuration.

So, this uneven distribution of charge is also one that makes a dipole moment. In differences, CO₂ is linear as there are no lone pairs on the central carbon atom, resulting in a symmetrical arrangement of atoms and a zero dipole moment.