CHM 101L M4 Fundamentals of Calorimetry Lab Report

2 1. Create a spreadsheet and graph of the data from Data Table 1, plotting temperature vs. time, and use the Y intercept to find the temperature at time 0 when the two volumes of water are mixed. a. Insert graph below. 0 2 4 6 8 10 12 0 10 20 30 40 50 f(x) = − 0.63 x + 45.07 f(x) = − 0.76 x + 43.27 Activity 1 Chart Water Temperature vs Time Trial 1 Temp(°C) Linear (Trial 1 Temp(°C)) Trial 2 Temp. (°C) Linear (Trial 2 Temp. (°C)) Time (min) Temperature (Celsius) Activities 2 and 3 Data Table 2 5g CaCl 2 10g CaCl 2 15g CaCl 2 5g NH 4 Cl 10g NH 4 Cl 15g NH 4 Cl Mass of water (g) 100g 100g 100g 100g 100g 100g Mass of salt (g) 5g 10g 15g 5g 10g 15g Moles of salt (g x mol/g) 0.045m 0.090m 0.135m 0.093m 0.187m 0.280m Initial Temperature (°C) T i 17 °C 17 °C 17 °C 17 °C 17 °C 17 °C Final Temperature (°C) T f 23 °C 30 °C 36 °C 13 °C 9 °C 6 °C Change in Temperature (°C) ∆T = T f - T i 6 °C 13 °C 19 °C -4 °C -8 °C -11 °C Heat absorbed by the solution (J) q w = -[c w x m w x -2636J -5983J -9142J 1757J 3681J 5293J © 2016 Carolina Biological Supply Company

5 6. Based on the data and graphs for calcium chloride and ammonium chloride, determine which compound to use and what quantity of each compound will be needed to make a chemical hot pack and cold pack. Both packs should be calculated based on using 100 g (100 mL) of water. The hot pack should reach 60 °C, and the cold pack should go down to 3.0 °C from a room temperature of 25 °C. Hot Pack: Compound needed to achieve 60 °C above room temperature: You would need 24.83g of CaCl 2 Cold Pack: Compound needed to achieve 3.0 °C: You would need 35.132g of NH 4 Cl 7. What were some potential sources of error in this investigation? Some potential sources of error could be the air temp outside of the cup. Also, I am not sure that I was able to fully dump the material into the water because I noticed that there was a small amount left behind on the tray. 8. Suggest some ways in which the calorimeter or lab protocol could be improved to have lower percentage of errors. If possible I would seal the calorimeter to prevent heat from escaping. You could also weight the tray before and after dumping it into the water to see how much residue is leftover, if any. I might also take a reading of the outside air temp if unable to seal the calorimeter. © 2016 Carolina Biological Supply Company