Vapor Pressure of Liquids

2013-10-23 4:51 pm

1. What is an enthalpy of vaporization for a liquid ?

2. A compound with a high vapor pressure has a ______ (high / low) enthalpy of vaporization. Explain

3. Make a prediction about the relative enthalpies of vaporization among the the two liquids, methanol and ethanol. Which will be higher ? Lower ? Explain.

回答 (1)

用戶4366

2013-10-23 5:46 pm

✔ 最佳答案

1. This is the latent heat of vaporization of the liquid. It is used for breaking the intermolecular force during vaporization.

2. A compound with a high vapor pressure has a _lower_ (high / low) enthalpy of vaporization.
Lower enthalpy of vaporization means easier to evaporate and hence results in a higher vapor pressure.

3. Intermolecular force within methanol and ethanol are the same, they are hydrogen bonding.
The other factor that affect the evaporation is the mass of molecule. Mass of ethanol is higher than that of methanol and leads to higher enthalpy of vaporization for ethanol.

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