To Determine Energy Lost by Calcium Chloride and Gained by Ammonium Nitrate When Dissolved in Water.

Topics: Energy, Endothermic, Exothermic Pages: 2 (453 words) Published: November 17, 2011
Experiment 2
Purpose: To determine energy lost by Calcium Chloride and gained by Ammonium Nitrate when dissolved in Water. Theory: Exothermic reactions are when net energy is lost in process of reaction. When solid calcium chloride (chemical formula CaCl₂) is placed in water, the calcium chloride dissolves and liberates heat in the process. Calcium chloride is one of the ingredients in instant "hot packs" sold in retail stores. Some concrete mixes incorporate calcium chloride to decrease drying time. Calcium chloride is also used as a de-icer. Endothermic reactions are when net energy is used in process of reaction. When we dissolve ammonium nitrate the temperature of water falls because the salt is gaining in potential energy. That is why many cold packs for athletes are made from this salt. Procedure:

1. We took a Styrofoam cup as our calorimeter. We measured its weight and added 70 ml of room temperature water and weighed it again. We determined the mass of water. We also measured its temperature. 2. We weighed a weighing paper and then sample of calcium chloride. Then we determined mass of sample. We did the same for Ammonium Nitrate. 3. We added the sample and measured the final temperature reading. 4. We measured the change in temperature of water.

Data | CaCl2| NH4NO3|
Mass of the calorimeter| 1.89 g| 1.89g|
Mass of Calorimeter and water| 70.50g| 70.63g|
Mass of the water| 70.50-1.89=68.61g| 70.63-1.89=68.74g| Mass of the paper| 0.99g| 0.87g|
Mass of paper and sample| 4.36g| 4.28g|
Mass of Sample| 4.36-0.99=3.37g| 4.28-0.87=3.41g|
Initial temperature of water| 22.0 0C| 22.80C|
Final temperature of Water| 30.00C| 19.00C|
Change in temperature| 30-22=80C| 19-22.8=-3.80C|
Calories gained or lost by water| 68.61*8=548.9 Calories| 68.74*-3.8=-261.2 Cal| Calories gained or lost by salt| -548. 9Cal| 261.2Cal|
Calories gained or lost per gram| -548.9/3.37=-162.9 Cal|...
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