Heat Of Fusion of Ice Lab Physics 221 PDF

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Heat Of Fusion of Ice Lara de Almeida and Abigail Jarratt Physics 221 Section 4 Aaron Kirby Performed: October 27, 2016 Submitted: November 3, 2016

Introduction The objectives of this experiment are to study the method of mixtures, the concepts of specific heat and latent heat of fusion, and to measure the heat of fusion of ice. The change in heat(ΔQ) of a material is directly proportional to the material’s mass and change in temperature when there is no change in its state. ΔQ = mcΔT In this equation, m is mass, T is temperature, and c is the specific heat of the material which means the amount of heat per unit mass to cause a unit change in temperature. When in a certain state, the specific heat is constant for a material. ΔT is the change from the final temperature to the initial temperature. ΔT = Tf-Ti ΔQ is positive when the body gains heat (final temperature is greater than intial) and negative when the body loses heat (final temperature is less than intial). When a change in state occurs, heat is either gained or lost without a change of temperature. This extra heat is needed to decreases the potential energy between the molecules. ΔQ = mL ΔQ is directly proportional to the mass of the material where L is a constant called latent heat, which is the amount of heat per unit, mass required to change a material from a solid to a liquid at the melting temperature. For example, when ice melts, the ice absorbs heat with no change in temperature.

When substances are mixed together so that they come into thermal equilibrium with each other it is called the method of mixtures. Thermal equilibrium means that the materials are at the same temperature so that there is no net transfer of heat between the materials. The heat gained by the system is equal to the heat lost by the system due to energy conservation.

Procedure The setup of this experiment consists of an aluminum cup insulated form and inside another aluminum container. The outer cup prevents heat loss and gain by the inner cup, which contains a mass of water where ice is dropped into it to melt, lowering the final temperature. We conducted three overall trials.

Data

Analysis We conducted three trials starting with taking the mass of the inner can (mc ) and then adding in water at about 32 degrees Celsius, then taking the mass of the inner can and the water (mcw ). From this calculation we subtracted the mass of the inner can from the inner can and water to find the mass of water (mw ). Next, we recorded the room and initial water temperature before adding ice to the cup (while lightly stirring). After waiting a bit for the ice to melt and for thermal equilibrium to take place, we recorded the final temperature of the can and water and massed the cup containing water and ice (mcwi ). We found the final mass of the ice by subtracting the mass of the cup and water. We then found the value of latent heat of fusion of ice by using the equation… [mi ci (Tfi – Tii )] + [mi Lf ] + [mi cw (Tfiw – Tiiw )]+ [mw cw (Tfw – Tiw )] + [mc cc (Tfc – Tic )] =0

[Heat gained by Ice] + [Heat gained by melting ice] + [Heat gained by melted ice] + [Heat lost by water] + [Heat lost by cup] = 0 By examining the final and initial temperatures we were able to condense this equation since most of the values were equal to each other. Tfiw = Tfw = Tfc Tiw = Tic 0 = Tiiw = Tfi Furthermore, we knew that the final temperatures of the melted ice, cup, and water at thermal equilibrium are all equal and the final temperature as ice turns to water is zero. After the ice has melted and before it has begun to warm up, the initial temperature of the water coming from the melted ice will also be zero. In addition, the temperatures of the cup and water are equal. Thus, yields the equation…

0 = -mi Lf We calculated a value of 82.79 for our first trial 82.93 for our second trial, and 81.85 for our third trial. Next, we compared these values to the accepted latent heat of fusion of ice value which was 80. Our calculations yielded a 3.49% difference for the first trial, a 3.67% for the second trial, and a 2.43% for the third trial. Overall we believe these percentages to be very low indicating that our experiment was successful.

Conclusion The objective of this lab was to find the latent fusion of ice using specific heat and methods of mixtures concepts. We found this experiment to be affirmative because our percent differences were all under 4% meaning that we conducted the process in an accurate manner. Nonetheless, possible errors in the lab could have came from the loss of heat from the calorimeter to its surrounding environment because when it is below room temperature it was absorb heat. When an experiment involves a temperature decrease below room temperature, beginning the experiment above room temperature may offset the heat absorbed from the environment. This can be adjusted by adding additional ice into the calorimeter....