Chemistry

Chloromethane (CH3Cl) has a higher boiling point than methane (CH4).

Both methane and chloromethane have simple molecular structure. In each compound, the molecules are held together by van der Waals forces.

Methane molecules are non-polar, which are held together by dipole - induced dipole attractions. Chloromethane molecules are polar, which are held together by instantaneous dipole - induced dipole attractions. Dipole - induced dipole attractions are stronger than instantaneous dipole - induced dipole attractions.

2006-12-14 17:37:59 補充：
The last paragraph should be :Methane molecules are non-polar, which are held together by instantaneous dipole - induced dipole attractions. Chloromethane molecules are polar, which are held together by dipole - dipole attractions.

2006-12-14 17:38:26 補充：
......Dipole - dipole attractions are stronger than instantaneous dipole - induced dipole attractions.

Chloromethane (CH3Cl) has a higher boiling point than methane (CH4).

As CH3Cl has a greater relative molecular mass than CH4, the van der Waals' force between CH3Cl molecules is stronger than CH4's, so it needs much more energy to break down this force.

Chloromethane (CH3Cl) has a higher boiling point than methane (CH4).

Both methane and chloromethane have simple molecular structure. In each compound, the molecules are held together by van der Waals' force.

Methane molecules are non-polar, which are held together by instantaneous dipole - induced dipole attractions. Chloromethane molecules are polar, which are held together by dipole - dipole attractions. Dipole - dipole attractions are stronger than instantaneous dipole - induced dipole attractions.

so it need more energy to break the connection between chloromethane molecules, so the b.p. of Chloromethane is higher

actually, the above passage are copy from the first answer, but i correct something wrong.

chloromethane
Because it has larger Van Der Waals' force between molecules and also it has higher molecular mass.