If the boiling point of H2O is 373 K, the boiling point of H2S will be
If the boiling point of H2O is 373 K, the boiling point of H2S will be
The correct option is D Less than 300 K
An explanation for the correct option:
The boiling point: The boiling point of a substance is the temperature at which the vapor pressure of the liquid is equal to the surrounding atmospheric pressure, thus facilitating the transition of the material between gaseous and liquid phases.
- We know when F, O or N atoms are attached to hydrogens atoms, a hydrogen bond will appear due to the high electronegativity difference between them.
- Water (H2​O) has hydrogen bonding and London forces. Hydrogen sulfide (H2​S) has only London forces. The reason why water has hydrogen bonding and hydrogen sulfide does not is because the oxygen in water is more electronegative than the sulfur in hydrogen sulfide. Hydrogen bonding only occurs between molecules that have hydrogen bonded to a very electronegative atom, which is either oxygen, fluorine, or nitrogen.
- A hydrogen bond is an intermolecular attraction between the hydrogen of one atom and the lone pair of electrons of another atom. In order for the bond to exist, the lone pair of electrons must belong to an electronegative atom, so there will be a great tendency for attraction.
(H2​O) is very strongly hydrogen bonded. These bonds require energy to break resulting in a higher boiling point.
(d) Less than 300 K: Very strong hydrogen bonding is present in H2O but no hydrogen bonding is present in because of its gaseous state, and because of that H2O has a higher boiling point than H2S.
An explanation for the incorrect option:
(a) Greater than 300 K but less than 373 K: Water molecules (H2O) is found in the liquid state because of hydrogen bonding. but is found in the gaseous state because Sulphur atoms don't show a hydrogen bond. now we know as well, that gas has a very low boiling point compared to a liquid. So this option is not correct.
(b) Equal to 373 K: At room temperature water is liquid and has a boiling point of 373 K due to hydrogen bonding. Whereas H2S is gas and has no hydrogen bonding. Hence the boiling point of H2S can't be equal to H2O but less than 300 K.
(c) More than 373 K: H2S molecules are involved in weaker hydrogen bonding than H2O molecules. This is because of the lower electronegativity of sulfur than oxygen. So, less energy is required to break the hydrogen bonds in H2S. Thus, the boiling point of H2S can't be higher than that of H2O.
Final Answer: Hence option (d) is correct.
Less than 300 K
An explanation for the correct option:
The boiling point: The boiling point of a substance is the temperature at which the vapor pressure of the liquid is equal to the surrounding atmospheric pressure, thus facilitating the transition of the material between gaseous and liquid phases.
- We know when F, O or N atoms are attached to hydrogens atoms, a hydrogen bond will appear due to the high electronegativity difference between them.
- Water (H2​O) has hydrogen bonding and London forces. Hydrogen sulfide (H2​S) has only London forces. The reason why water has hydrogen bonding and hydrogen sulfide does not is because the oxygen in water is more electronegative than the sulfur in hydrogen sulfide. Hydrogen bonding only occurs between molecules that have hydrogen bonded to a very electronegative atom, which is either oxygen, fluorine, or nitrogen.
- A hydrogen bond is an intermolecular attraction between the hydrogen of one atom and the lone pair of electrons of another atom. In order for the bond to exist, the lone pair of electrons must belong to an electronegative atom, so there will be a great tendency for attraction.
(H2​O) is very strongly hydrogen bonded. These bonds require energy to break resulting in a higher boiling point.
(d) Less than 300 K: Very strong hydrogen bonding is present in H2O but no hydrogen bonding is present in because of its gaseous state, and because of that H2O has a higher boiling point than H2S.
An explanation for the incorrect option:
(a) Greater than 300 K but less than 373 K: Water molecules (H2O) is found in the liquid state because of hydrogen bonding. but is found in the gaseous state because Sulphur atoms don't show a hydrogen bond. now we know as well, that gas has a very low boiling point compared to a liquid. So this option is not correct.
(b) Equal to 373 K: At room temperature water is liquid and has a boiling point of 373 K due to hydrogen bonding. Whereas H2S is gas and has no hydrogen bonding. Hence the boiling point of H2S can't be equal to H2O but less than 300 K.
(c) More than 373 K: H2S molecules are involved in weaker hydrogen bonding than H2O molecules. This is because of the lower electronegativity of sulfur than oxygen. So, less energy is required to break the hydrogen bonds in H2S. Thus, the boiling point of H2S can't be higher than that of H2O.
Final Answer: Hence option (d) is correct.
