In chemistry, which substance CO2 or H20 has stronger intermolecular forces of attraction? Explain in terms of Molecular Polarity.

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ncchemist eNotes educator| Certified Educator

We are looking at the intermolecular forces between water (H2O) and carbon dioxide (CO2).  Intermolecular forces are the forces of attraction between neighboring molecules in a sample of a chemical.  Water is a highly polar compound that consists of two hydrogens and two electron pairs surrounding an oxygen.  The molecule has a bent shape, and the hydrogen atoms are attracted to the oxygen electron pairs in neighboring molecules.  This is called hydrogen bonding and it is a very strong intermolecular force.  Carbon dioxide is a linear molecule with a carbon in the center flanked by two oxygens.  It has no net internal molecular polarity since the two carbon-oxygen bonds in opposing directions cancel each other out.  As a result, it has very weak intermolecular forces and no hydrogen bonding.  This means that water has much stronger intermolecular forces of attraction than CO2.  This can be readily seen by the fact that water is a liquid and CO2 is a gas.  A liquid will have more attractive forces between its molecules than a gas due to the major difference in density between the two phases.

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