which of the following has lowest vapour pressure ?
1 water
2 bromine
3 ethyl alcohol
4 ether
Probably ether but why don't you look up the vapor pressure of each at room temperature and then you will know.
To determine which substance has the lowest vapor pressure, we need to compare the intermolecular forces of attraction between the molecules of the substances. The substance with the strongest intermolecular forces will have the lowest vapor pressure.
The strength of intermolecular forces primarily depends on the type and size of the molecules. Generally, larger molecules have stronger intermolecular forces.
Water (choice 1) has a high boiling point and significant intermolecular forces due to its hydrogen bonding. This makes it less volatile and have a lower vapor pressure compared to the other substances.
Bromine (choice 2) consists of diatomic molecules (Br2), which have weaker intermolecular forces compared to water. Therefore, bromine has a higher vapor pressure than water.
Ethyl alcohol (choice 3) also has weaker intermolecular forces compared to water and bromine. While it can form hydrogen bonds, it has larger molecular size and weaker bond strength. Therefore, ethyl alcohol has a higher vapor pressure compared to water.
Ether (choice 4) has weaker intermolecular forces compared to the other substances mentioned. It is a small molecule and lacks hydrogen bonding capability. Therefore, ether has the lowest vapor pressure among the given choices.
Therefore, the correct answer is 4) ether.
To identify the substance with the lowest vapor pressure among water, bromine, ethyl alcohol, and ether, we need to understand what vapor pressure is.
Vapor pressure refers to the pressure exerted by the vapor (gas phase) of a substance in equilibrium with its liquid or solid phase. It is a measure of the tendency of a substance to evaporate and escape from its liquid or solid form into the gas phase.
In general, substances with stronger intermolecular forces (such as hydrogen bonding) will have lower vapor pressures because the attractive forces between particles are stronger, making it more difficult for the substance to transition into the gas phase.
Among the given options:
1. Water (H2O) has hydrogen bonding, resulting in stronger intermolecular forces and a lower vapor pressure.
2. Bromine (Br2) is a diatomic molecule with weaker intermolecular forces compared to water but stronger than ethyl alcohol and ether.
3. Ethyl alcohol (C2H5OH) also has hydrogen bonding and exhibits stronger intermolecular forces than bromine and ether.
4. Ether (C2H5OC2H5 or CH3CH2OCH2CH3) does not have any hydrogen bonding, making it the substance with the weakest intermolecular forces and hence the highest vapor pressure. Therefore, ether has the lowest boiling point and the highest tendency to evaporate.
So, the substance with the lowest vapor pressure among the given options is ether (option 4).