Question

Which statement explains why methane has a lower boiling point than water

Answer 1

Ответ:

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Answer 2

Methane (CH4) has a lower boiling point than water (H2O) primarily because of differences in their molecular structures and intermolecular forces. Here's a breakdown of the key factors:

1. Molecular Mass:

   • Methane is a simple hydrocarbon composed of one carbon atom (C) bonded to four hydrogen atoms (H). Its molecular mass is relatively low, which means its molecules are lighter.
   • Water, on the other hand, consists of two hydrogen atoms and one oxygen atom (H2O). Its molecular mass is higher compared to methane.

2. Molecular Shape:

   • The geometry of the molecule also plays a role. Methane is a tetrahedral molecule with a symmetrical arrangement of its hydrogen atoms around the central carbon atom.
   • Water has a bent or V-shaped molecular geometry due to the presence of two lone pairs of electrons on the oxygen atom. This bent shape creates a polarity in the molecule.

3. Intermolecular Forces:

   • Intermolecular forces are the attractive forces that exist between molecules in a substance. They influence the boiling points of substances.
   • Methane molecules primarily experience London dispersion forces (Van der Waals forces) due to the temporary fluctuations in electron density around the molecule. These forces are relatively weak.
   • Water molecules, on the other hand, can form hydrogen bonds with each other due to the polarity of the molecule. Hydrogen bonds are stronger than dispersion forces and require more energy to break.

Because of these factors, water has stronger intermolecular forces (hydrogen bonds) and a higher molecular mass than methane. As a result, it takes more energy to overcome these forces and separate water molecules, which leads to a higher boiling point for water compared to methane. Methane, with its weaker intermolecular forces and lower molecular mass, boils at a much lower temperature.