Jason Jarrell

Chemistry II

12-8-99

Heat of Fusion

Objective: The objective of this experiment is to find the heat of fusion of water by using a calorimeter. The calorimeter will be used to melt ice in water to find the heat of fusion.

Theory: Heat of fusion is known to be the amount of heat that it takes to allow one mole of a substance to turn from solid to liquid. The heat of fusion of water is known to be 80 cal/mol. This experiment will use a calorimeter with distilled water and ice to find an experimental value of heat of fusion of water. Equations used in this experiment will be LFM1 = M2CT where LF is the heat of fusion, M1 is the mass of the substance being melted (the ice), M 2 is the mass of the substance that is doing the melting (the water), C is the specific heat of the substance (water is one calorie per gram per degree), and T is the change in temperature.

Procedure: The following materials will be needed for this experiment, a cup, a thermometer, distilled water, ice, and a scale. The first step is to find the mass of the cup without anything in it. After that fill it about half full with distilled water, and find the mass of that. After the mass of the cup and water is measured, put about five or six normal blocks of ice in to the cup. Use the thermometer to stir the mixture. Every 15 seconds record the temperature of the mixture. When the temperature has leveled off, use a fork to pick out any blocks of ice that are left.

Data & Calculations:

Mass of cup: 3.39 g

Mass of cup and water: 169.17 g

Mass of cup, water and ice: 208.11 g

Mass of water: 165.78g

Mass of ice: 38.94 g

Change in temperature: 18.9 C

(38.94 g)X = (165.78 g)(1 cal/gram C)(18.9 C)

38.94 g X = 3133.242 cal

X = 80.46 cal/g

80.46 – 80 = .6 % error

80

Conclusion & Discussion: This experiment was good to show how find an experimental value of heat of fusion of a substance. Some of the possible sources of error could have been:

 There could have been human error in reading equipment.

 There could have been equipment error in measuring.

 Some extra water could have come out when digging out the ice.

 The ice was tap water and not distilled.

 Some water could have been splashed out when stirring.

 Some heat could have been lost into the cup.

 Some heat could have been lost to the environment.

Word Count: 445