Association of Energy with System Changes in an Endothermic and Exothermic Reaction

Topics: Thermodynamics, Enthalpy, Energy Pages: 3 (574 words) Published: May 13, 2013
Calorimetry Lab

Calorimetry Lab
The purpose of this lab is to use the calorimetry to determine how energy is associated with a system changes in an endothermic and exothermic reaction and to use this information to calculate molar enthalpy of various salts. Hypothesis:

I hypothesize that when water is added to the ammonium nitrate the temperature of the surroundings will decrease and when water is added to the calcium chloride the temperature of the surroundings will increase. Materials

Equipment: Reagents:
* Styrofoam cup ammonium nitrate
* graduated cylinder calcium chloride
* electronic balance 
* thermometer 
* tap water
* 100ml beaker x2

Materials not used: none
Materials that were used but not listed: none

1. Put on safety goggles and aprons
2. Measure 100ml in the graduated cylinder. Transfer the water to the Styrofoam cup and record the initial temperature of the water  3. Weigh accurately 3g of NH4NO3 to the water and place the lid onto the cup. Gently and continually stir the solution with the thermometer. 4. With constant observation of the temperature until it remains constant for about 15-20 seconds. Record the final temperature  5. rinse the cup, dry it thoroughly 

6. Repeat steps 1-5 of the experiment using 3g of calcium chloride in place of ammonium nitrate  Steps not used: none
Changes to the lab: did not gently stir the solution with the thermometer because it had no room to move in the styrofoam cup. Instead the calorimeter was gently shaken to dissolve the chemicals. Chemicals and their hazards:

Ammonium nitrate forms a mild acid when mixed with water. This acid can cause irritation to the eyes, nose, and skin. Inhalation of high concentrations of ammonium nitrate dust can cause respiratory tract irritation CaCl2

Calcium chloride can cause skin irritation and possibly burns, especially if water is present. In...
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