Molar heat of fusion: the heat (enthalpy, energy) needed to transform a solid in liquid (expressed in kJ/mol).
Molar heat of vaporization: the heat (enthalpy, energy) needed to transform a liquid in gas (expressed in kJ/mol).
Fusion refers to the phase change from liquid to solid (or vv) and vaporization refers to the phase change from liquid to gas (or vv). Heat is either absorbed or released from the substance when these events occur. We use the molar enthalpies to calculat exactly how much heat is transferred during these processes. Ex .. If we are to boil (vaporize) 3 moles of some substance with a known molar enthalpy of vaporization of 120 KJ/mole then we multiply. 3 moles x 120 KJ/mole = 360 KJ of energy is needed for the vaporization to take place.
The heat of vaporization of water is greater than its heat of fusion. Specifically, the heat of vaporization is approximately 2260 joules per gram, while the heat of fusion is about 334 joules per gram. This means that it requires significantly more energy to convert water from a liquid to a gas than to change it from solid to liquid.
In SI units: kJ/kmol
The heat of fusion is the energy required to change a substance from solid to liquid at its melting point, while the heat of vaporization is the energy required to change a substance from liquid to gas at its boiling point. Both values are specific to each substance and represent the amount of energy needed to break intermolecular forces during phase changes, with vaporization requiring more energy than fusion due to the additional change in state.
When liquid molecules absorb enough heat energy, evaporation occurs.
It is a known fact : Molar heat of sublimation = molar heat of fusion + molar heat of vaporization so, molar heat of vaporization = molar heat of sublimation - molar heat of fusion Mv = 62.3 kJ/mol - 15.3 kJ/mol Mv = 47 kJ/mol.
The latent heat of evaporation
The molar heat of vaporization can be estimated by using the Clausius-Clapeyron equation, which relates the vapor pressure of a substance to its temperature and molar heat of vaporization. By knowing the temperature change and the corresponding increase in vapor pressure, calculations can be made to determine the molar heat of vaporization.
molar heat of fusion
Fusion refers to the phase change from liquid to solid (or vv) and vaporization refers to the phase change from liquid to gas (or vv). Heat is either absorbed or released from the substance when these events occur. We use the molar enthalpies to calculat exactly how much heat is transferred during these processes. Ex .. If we are to boil (vaporize) 3 moles of some substance with a known molar enthalpy of vaporization of 120 KJ/mole then we multiply. 3 moles x 120 KJ/mole = 360 KJ of energy is needed for the vaporization to take place.
The heat of vaporization of water is greater than its heat of fusion. Specifically, the heat of vaporization is approximately 2260 joules per gram, while the heat of fusion is about 334 joules per gram. This means that it requires significantly more energy to convert water from a liquid to a gas than to change it from solid to liquid.
In SI units: kJ/kmol
First things first: it's actually spelled "enthalpy", which might be why you're not finding it.If you want a number, you will need to specify a substance.If you just want to know what it means, then in simple terms it's the amount of energy required to evaporate one mole of the substance.
The heat of fusion is the energy required to change a substance from solid to liquid at its melting point, while the heat of vaporization is the energy required to change a substance from liquid to gas at its boiling point. Both values are specific to each substance and represent the amount of energy needed to break intermolecular forces during phase changes, with vaporization requiring more energy than fusion due to the additional change in state.
When liquid molecules absorb enough heat energy, evaporation occurs.
Latent heat is the amount of thermal energy required to change the phase of a substance. Latent heat of fusion is the amount of energy needed to change it from a solid to liquid or a liquid to solid, and the latent heat of vaporization is the thermal energy needed to change from a liquid to gas or a gas to liquid. For example, in the equation Q = mL, Lfusion (latent heat of fusion) for water is 75.5 cal/gram. Lvaporization (latent heat of vaporization) for water is 539 cal/gram. Substances have different latent heats.
The heat of fusion is the energy required to change a substance from a solid to a liquid, while the heat of vaporization is the energy needed to change a substance from a liquid to a gas. Both are types of phase changes that require specific amounts of energy to occur.