1. Changes in Temperatures By Jessa, Kyle, and Brandon

2. Purpose & Hypothesis Purpose: To find what happens to the temperature when a solute is dissolved into a solvent. Hypothesis: The temperature will decrease as the solute is added.

3. Independent and Dependent Variables IV: Amount of calcium chloride/ sodium chloride (g) DV: Temperature (degrees Celsius) Levels: 0g.2g (1g).4g (2g).6g (3g).8g (4g) 1g (5g) 4 trials

4. Constants ~~~ Type of solute ~~~ Amount of water (50 mL) ~~~ Styrofoam cup ~~~ Temperature sensors ~~~ Type of water (tap)

5. Procedures 1.Measure 50 mL of water and put into the Styrofoam cup 2.Record starting temperature 3.Measure.2g of CaCl 2 / 1 g of NaCl and add to the cup 4.Record the temperature after 1 minute 5.Calculate the change in temperature 6.Repeat steps 1-5 using.4,.6,.8, and 1g of CaCl 2 / 2,3,4,5g of NaCl

6. Results (Calcium Chloride) Amount of CaCl2 (g) Starting temp. (degrees Celcius) Ending temp. (degrees Celcius) Change in temperature (degrees Celcius) 021.4 0.221.422.81.4.422.823.7.9.623.724.81.1.824.826.41.6 126.428.01.6

7. Results (continued)

8. Summary of Data According to the data, when the calcium chloride is mixed with the water, the temperature increased by an average of 1.32 degrees Celsius. When the sodium chloride was added with the water, it decreased. As.2 grams of calcium chloride were added, 6.6 degrees per gram was the average rate of change. As 1 grams of sodium chloride were added,.9 degrees per gram was the average rate of change. Our hypothesis that the temperature would decrease was correct for the sodium chloride but proved incorrect for the calcium chloride. When calcium chloride and sodium chloride are dissolved into water, ionic bonds are broken and formed. When calcium chloride was put into the water, there was an exothermic change and energy was released, raising the temperature. When sodium chloride dissolved in water an endothermic change happened, resulting in a temperature decrease.