Each of the following substances is a liquid at –50°c. place these liquids in order of increasing vapor pressure: dimethyl ether (ch3och3), propane (c3h8), and ethanol (ch3ch2oh).a) propane < ethanol < dimethyl etherb)ethanol < propane < dimethyl etherc)propane < dimethyl ether < ethanold)ethanol < dimethyl ether < propanee)dimethyl ether < ethanol < propane

Increasing vapor pressure order -

propane > dimethyl ether > ethanol

Explanation:

Vapor pressure - the pressure exerted the gaseous molecules , on the walls of the container is called the vapor pressure.

Boiling point - the temperature at which the the vapor pressure of the liquid equals the external atmospheric pressure.

Both boiling point and vapor pressure are linked by the inter molecular forces between the atoms.

The compound with stronger inter molecular forces are tightly held , hence more amount of energy is required to vaporize. Therefore, higher boiling point , and in turn the vapor pressure will be lower .

And the compound with weaker inter molecular forces are loosely held , hence less amount of energy is required to vaporize. Therefore, lower boiling point , and in turn the vapor pressure will be higher .

Therefore,

Ethanol has lowest vapor pressure , because at lower temperature , it has H - bonding , hence, its boiling point is more, therefore, less vapor pressure.

Dimethyl ether has vapor pressure more than ethanol as it has weaker dipole - dipole interactions as compared to strong H - bonding .

Propane has maximum vapor pressure among all , because of lower molecular mass than others , it can easily vaporize into vapors.

Hence,

Increasing vapor pressure order -

propane > dimethyl ether > ethanol

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