Question

Calculate the amount of heat energy, q, produced in each reaction. Use 1.03 g/mL for thedensity of all solutions. Use the specific heat of water, 4.18 J/(g•°C), for all solutions.

The temperature change in part 3 was 15.5 degrees celsius.

Temperature change in part 4 was -1.2 degrees celsius.

Then determine the enthalpy change for each reaction in terms of kJ/mol of each reactant.

The molarity of NaOH is 2.0 M.

Part III Conduct the Reaction Between Solutions of NaOH and HCI 12. Nest a Styrofoam cup in a beaker, as shown in Figure 1. Measure out 50.0 mL of 2.0 M HCL solution into the foam cup. Lower the Temperature Probe into the solution. CAUTION: Handle the hydrochloric acid with care. It can cause painful burns if it comes in contact with the skin. 13. Measure out 50.0 mL of NaOH solution prepared in part 1, but do not add it to the HCL solution yet. CAUTION: Handle the sodium hydroxide solution with care. 14. Conduct the reaction. f. Start data collection and obtain the initial temperature of the HCI solution. g. After three or four readings have been recorded at the same temperature, add the 50.0 mL of NaOH solution to the Styrofoam cup all at once. Use a glass stirring rod to stir the reaction mixture continuously until the temperature reaches a peak and begins to fall. h. Data collection will end after three minutes. If the temperature readings are no longer changing, you may stop the trial early. i. To examine the data pairs on the displayed graph, select any data point. As you move the examine line, the temperature values of each data point are displayed to the right of the graph. j. Record the initial and maximum temperatures in your data table. 15. Rinse and dry the Temperature Probe, Styrofoam cup, and the stirring rod. Dispose of the solution as directed. Part IV Conduct the Reaction Between Solutions of NaOH and NHACI 16. Measure out 50.0 mL of the NaOH solution prepared in part I into a nested Styrofoam cup (see Figure 1). Lower the tip of the Temperature Probe into the cup of NaOH solution. 17. Measure out 50.0 mL of the NH4Cl solution prepared in part II, but do not add it to the NaOH solution yet. 18. Conduct the reaction. a. Start data collection. b. After three or four readings have been recorded at the same temperature, add the 50.0 mL of NH4Cl solution to the Styrofoam cup all at once. Use a glass stirring rod to stir the reaction mixture continuously until the temperature reaches a peak and begins to fall. c. Data collection will end after three minutes. If the temperature readings are no longer changing, you may stop the trial early. d. Examine the graph as before to determine and record the initial and maximum temperatures of the reaction. 19. Rinse and dry the Temperature Probe, Styrofoam cup, and the stirring rod. Dispose of the solution as directed.

Answer 1

Part III Total mass of solution 1.03g m = (50.0 mL + 50.0 mL) 1.0 mL =103 g Specific heat of solution, s=4.18J/g °C Temperature change, AT = 15.5 °C Haet gained by solution q=mXSXAT = 103 g(4.18J/g °C)*15.5°C = 6673.4) Heat of reaction AH =-9 =-6673.4J Enthalpy change of reaction in kJ/mol of each reactant -6673.4J 1kJ L 1000J 2.0M NaOH 50.0 mLx- 1000 mL = -66.7 kJ/mol NaOH -6673.4J 1 kJ L 1000 J 2.0M HCI x 50.0 mL X- 1000 mL = -66.7 kJ/mol HCI AHAN AH

Part IV Total mass of solution m=(50.0mL + 50.0 mL)x 1.03 g 1.0 mL = 103 g Specific heat of solution, s=4.18J/g °C Temperature change, AT =-1.2°C Haet gained by solution q=mXsX AT =103gx(4.18J/g °C)*(-1.2)°C =-516.71 Heat of reaction AH =-9 =-(-516.7J) = 516.73 Enthalpy change of reaction in kJ/mol of each reactant 516.7J IL | 1000 J 2.0M NaOH x 50.0 mLx- 1000 mL = 5.17 kJ/mol NaOH 516.7) AH IL 1000 J 2.0M NH Cl< 50.0 mLx 1000 mL 5.17 kJ/mol NHẠC 1kJ AH = 7 1kJ