The Latent Heat of Vaporization of Water
Aim:
The aim is to determine the latent heat of vaporization of water by doing an experiment of boiling water.
Theory:
The latent heat of vaporization is the amount of energy that is required to transfer a kg of liquid from the liquid state to the gaseous state. This transformation appears, when water is heated. The temperature of the water keeps increasing, until it has reached its boiling point at 100oC, where it remains until the heater gets turned off. If the water is still getting heated, it absorbs thermal energy, which turns the water into water vapour (steam) because of the separation of the molecules. All atoms “vibrate” (move), the hotter temperature they contain, the more they vibrate. This happens when you heat water; the bonds holding the water molecules together become unstable and therefore they separate because of the high temperature. So basically; when water is heated and turns into steam (gas), the H2O (water molecule) molecule gets broken into two H atoms and one O atom, which are gasses. And because of this transformation and as water is boiling, the weight of the water will be less.
The table value of the latent heat of the vaporization of water is 2300000 J/kg, which means: To change each kilogram of water into steam, 2300000 J are required to be transferred. (Source: cnx.org)
To measure the specific latent heat of vaporization of water you will need to use this equation: Energy transferred=mass × specific latent heat of vaporization, in symbols: E=mL m= The amount of water, which is boiled away.
E= power × time= The power of the heater and the taken time