Latent Heat of Fusion
Activity # 02
DE BORJA, C. A., DE CHAVES, N., DE LOS SANTOS, G. P., DEL MUNDO J., DIN, J. A., DIONISIO, J. D. Civil Engineering Department, College of Engineering,
The purpose of this experiment is to determine the Latent Heat of Fusion of ice. In this experiment, the heat of fusion of ice will be determined by using the method of mixtures (Quantity of heat lost = Quantity of heat gained).
When a substance changes phase, that is it goes from either a solid to a liquid or liquid to gas, the energy, it requires energy to do so. The potential energy stored in the interatomic forces between molecules needs to be overcome by the kinetic energy the motion of the particles before the substance can change phase. The energy required to change the phase of a substance is known as a latent heat. The word latent means hidden. When the phase change is from solid to liquid we must use the latent heat of fusion, and when the phase change is from liquid to a gas, we must use the latent heat of vaporization.
When a solid has reached its melting point, additional heating melts the solid without a temperature change. The temperature will remain constant at the melting point until the entire solid has melted. The amount of heat needed to melt the solid depends only on the mass of the solid. We have:
Q = MLf EQ. 1
Where Q is the amount of heat absorbed by the solid, M is the mass of the solid and Lf is The latent heat of fusion measured in cal/g (to fuse means to melt). Ice will be added to a calorimeter containing warm water. The heat energy lost by the water and calorimeter does two things:
1. It melts the ice;
2. It warms the water formed by the melting ice from zero to the final temperature.
Heat lost = Heat gained
Heat lost by warn water = heat needed to melt ice + heat needed to warm water which was once ice MwCw (Tw - Tf) = MiceLf + MiceCw (Tf- 0)...
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