Calorimetry: Specific Heat and Heat of Solution

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Summary
These experiments were conducted to find the specific heat of a metal as well as the heat of solution of a solid. Both experiments required the use of calorimetry to measure heat flow and temperature change. The specific heat of the metal was found by heating it in boiling water before transferring it to the calorimeter that was partially filled with water. After shaking the calorimeter, the temperature change was measured and recorded. This information was used to calculate the specific heat. The heat of solution of a solid was found similarly. The solid sample was added to the water in the calorimeter and gently swirled. After the solid completely dissolved and the temperatures reached equilibrium, the changes were measured Introduction

Calorimetry is often used to observe and measure heat flow between two substances. It is useful in providing such information because its contents are isolated. Therefore, calorimetry can measure only the heat flow of its contents. Heat flow is measured as it travels from a higher temperature to a lower one. Experiment A required solving for the specific heat of a metal. Specific heat is an amount of heat required to raise the temperature of one gram of anything one degree Celsius. Specific heat was calculated using several equations. First heat flow of water was solved by using the equation: Q water = C x m x  T

Heat flow = Specific Heat x mass x (Final Temperature- Initial Temperature). After finding the heat flow of the water, the heat flow of the metal was calculated using another equation: Q water = - Q metal or Q water = -(C x m x  T) metal

This equation was rearranged to solve for the specific heat of the metal. The molar mass of the metal was found by using the equation: MM = 25 / C (J/g° C)
Experiment B was conducted to find the heat of solution of an unknown solid. After finding the heat flow of the water, enthalpy change of the reaction was found by using the equation: Q reaction =  H reaction = -Q water.

This answer was then divided by the mass of the solid to find the heat of solution per gram of solid sample. The reaction is considered endothermic if the temperature was reduced, and it is exothermic if the temperature increased.

Materials
Experiment A:Experiment B:

2 Styrofoam coffee cups 2 Styrofoam coffee cups
2 Plastic lids2 Plastic lids
Large beaker Beaker
Test tube & stopper Sample of solid (NH4NO3)
Thermometer Water
Metal sample Thermometer
Water Balance scale
Bunsen burner
Ring stand
Balance scale

Methods
Experiment A:
1. The mass of the calorimeter (both stacked cups and lids) was found. 2. The mass of the stoppered test tube was found.
3. The calorimeter was filled with the metal (an inch from the bottom). This was done solely for measuring purposes. 4. The measured out amount of metal was poured into the test tube and stoppered. The mass of these was found. 5. The calorimeter was filled with water (to the same one inch line as the metal had been). This mass was then found. 6. The mass of the water was found by subtracting the mass of the calorimeter from the mass of the calorimeter plus water. 7. The mass of the metal was found by subtracting the mass of the stoppered test tube plus metal from the mass of the stoppered test tube. 8. 2/3 of the beaker was filled with water. The stoppered test tube plus metal was then placed inside of the beaker. 9. The beaker was placed on the ring stand over the Bunsen burner. 10. The water’s temperature in the calorimeter was measured. (initial temp.) The initial temperature of the metal was assumed to be 100° C. 11. When the water in the beaker began to boil, the test tube was removed. 12. The metal was then quickly poured into the calorimeter.

13. A thermometer was inserted through both lids, and the calorimeter was slightly shaken until the temperatures reached equilibrium (final temp.). 14. Data was then recorded and...
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