19c Latent Heat of Fusion - 1 -
Latent Heat of Fusion
Introduction
The purpose of this lab 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).
Equipment
Computer w/ Logger Pro SW Triple Beam Balance Water
Calorimeter Digital Scale
Digital Themometer Ice
Theory
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 ALL
of the 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) Eq. 2.
* Note: The mass of the melted water is the same as the mass of the ice.
where Mw = mass of warm water initially in calorimeter
Mice = mass of ice and water from melting
Cw = specific heat of water
Lf = heat of fusion of ice
Tw = initial temperature water
Tf = equilibrium temperature of mixture
