Which of the following molecules has the highest boiling point? CH4,BH3,NH3, SH2?
I don't believe BH3 can be isolated. Of the others, NH3 must have the highest b.p. because of the possibility of H bonding
To determine which molecule has the highest boiling point, we need to consider the intermolecular forces between the molecules.
1. CH4 (methane): This molecule is nonpolar, and its only intermolecular force is London dispersion forces. London dispersion forces typically increase with the number of electrons in a molecule, and since methane has the least number of electrons among the given options, its intermolecular forces would be the weakest.
2. BH3 (borane): This molecule is also nonpolar, so it only experiences London dispersion forces. However, boron is less electronegative than carbon in methane, meaning borane has an even weaker intermolecular force.
3. NH3 (ammonia): Ammonia is a polar molecule due to the difference in electronegativity between nitrogen and hydrogen atoms. It experiences London dispersion forces and dipole-dipole interactions. These dipole-dipole interactions are stronger than the London dispersion forces acting in methane or borane.
4. SH2 (hydrogen sulfide): Hydrogen sulfide is similar to ammonia as it is also a polar molecule. It experiences London dispersion forces and dipole-dipole interactions.
Comparing NH3 and SH2, sulfur is less electronegative than nitrogen, indicating that NH3 will have stronger dipole-dipole interactions. Therefore, NH3 has higher intermolecular forces and a higher boiling point than SH2.
In conclusion, NH3 (ammonia) has the highest boiling point among CH4, BH3, NH3, and SH2.
To determine which molecule has the highest boiling point among CH4, BH3, NH3, and SH2, we need to consider their molecular structures and intermolecular forces. The boiling point of a molecule is primarily determined by the strength of the intermolecular forces between its molecules.
In this case, we are comparing molecules with similar molecular structures but different atoms bonded to them: CH4 (methane), BH3 (borane), NH3 (ammonia), and SH2 (hydrogen sulfide).
Methane (CH4) consists of a carbon atom bonded to four hydrogen atoms. Borane (BH3) consists of a boron atom bonded to three hydrogen atoms. Ammonia (NH3) consists of a nitrogen atom bonded to three hydrogen atoms. Hydrogen sulfide (H2S) consists of a sulfur atom bonded to two hydrogen atoms.
The strength of intermolecular forces depends on the polarity of the molecule and the presence of hydrogen bonding or dipole-dipole interactions.
Methane (CH4) is a nonpolar molecule, and its only intermolecular force is the weak London dispersion force.
Borane (BH3) and ammonia (NH3) are both polar molecules since they have a central atom bonded to atoms of different electronegativity. Borane (BH3) has three polar B-H bonds, while ammonia (NH3) has three polar N-H bonds. Both molecules exhibit dipole-dipole interactions in addition to London dispersion forces.
Hydrogen sulfide (H2S) is also a polar molecule due to the electronegativity difference between sulfur and hydrogen. It has two polar S-H bonds and exhibits dipole-dipole interactions and London dispersion forces.
Among the given options, ammonia (NH3) has the highest boiling point. This is because ammonia can form stronger intermolecular attractions through hydrogen bonding than the other molecules. Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom (e.g., nitrogen or oxygen) and interacts with another electronegative atom. In the case of ammonia, the hydrogen atom can form hydrogen bonds with the lone pairs on the nitrogen atom of another ammonia molecule. This extra intermolecular attraction makes it more difficult to break the intermolecular forces and therefore increases the boiling point of ammonia compared to the other molecules.
So, NH3 has the highest boiling point among CH4, BH3, NH3, and SH2.