CHEM Act B5 HEAT-SI Lab Report Heat Relationships in Physical and Chemical Processes

Last Name, First Name Lab Instructor
Monday 5:30 PM
Date Lab Day Lab Start Time

Act B5 HEAT-SI Lab Report Heat Relationships in Physical and Chemical Processes

Parts I - II
Act B5 Online URL: http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/
thermochem/heat
_soln.html

The computer will simulate a calorimetry experiment involving dissolving various ionic salts in
water. The following compounds should be available for testing: ammonium nitrate, sodium
nitrate, calcium nitrate, magnesium nitrate, sodium chloride, calcium chloride, ammonium
chloride, magnesium chloride.

Part I Measure Heat of a Physical Process
Test all eight of the compounds using the same mass value for each. Some of your compounds
may cause an increase in temperature of the solution, other compounds could cause a decrease
in the temperature of the solution.

Write a specific question that you can answer as a result of performing your calorimetry
experiment.
• Does the breaking of bonds cause the temperature of the solution to change?

Part I A. Design and carry out an experiment to determine the change in enthalpy, H (kJ), for
the dissolving process for the nine ionic solids.

1. Write the chemical formulas for all eight ionic solids.
Ionic Solid Chemical Formula
Ammonium nitrate (NH4)(NO3)
Sodium nitrate Na(NO3)
Calcium nitrate Ca(NO3)2
Magnesium nitrate Mg(NO3)2
Sodium chloride NaCl
Calcium chloride CaCl2
Lithium chloride LiCl
Magnesium chloride MgCl2
Ammonium chloride NH4Cl

2. In your experiment, identify the independent and dependent variables.
• Independent Variable: Ionic Salts
• Dependent Variable: Change in Temperature

3. What is the magnitude and unit of the control variable in your experiment?



1

, • The control variables in this experiment includes the mass of compound and the
volume of water. Each ionic salt contained a mass of 0.50 grams and 20mL volume of
water. The initial temperature prior to heating is also set at 24.00 °C as well.
• Mass of Compound: 0.50 grams
• Volume of H2O: 20.00 mL
• Initial Temperature: 24.00 °C

4. Write equations that describe the dissolving process for each salt. Classify each process
as endothermic, exothermic, or neither after collecting the data.
Ionic Solid Chemical Equation Type Energy Change
+ -
Ammonium nitrate NH4NO3 (s) + H2O(l)NH3 (aq) + NO3 (aq) Endothermic
-
Sodium nitrate 2+
NaNO3 (s) + H2O(l)Na (aq) + NO3 (aq) Endothermic
-
Calcium nitrate 2+
Ca(NO3)2 (s) + H2O(l)Ca (aq) + 2NO3 (aq) Endothermic
-
Magnesium nitrate 2+
Mg(NO3)2 (s) + H2O(l)Mg (aq) + 2NO3 (aq) Exothermic
Sodium chloride NaCl (s) + H2O(l)Na+(aq) + Cl- (aq) Exothermic
Calcium chloride 2+ -
CaCl2 (s) + H2O(l)Ca (aq) + 2Cl (aq) Exothermic
Lithium chloride LiCl (s) + H2O(l)Li+(aq) + Cl- (aq) Exothermic
Magnesium chloride N/A N/A
+ -
Ammonium chloride NH4Cl (s) + H2O(l)NH4 (aq) + Cl (aq) Endothermic

5. List the assumptions and or information that you need to make in order to do
the calculations.
• Some information we need to know in order to make calculations are the number
of moles, pressure, and volume
• We also need to assume that no heat is gained or lost from the
surrounding environment
6. In your experiment, identify the system.
• The system are the reactants inside the calorimeter

7. In your experiment identify the surroundings.
• The surrounding environment is the water.

8. In your experiment, what gains heat energy?
• Endothermic Reactions: The system gains heat from itself in order to proceed

9. In your experiment what loses heat energy?
• Exothermic Reactions: The system loses heat to the surroundings

10. Report the heat of reaction (qRxn) for each ionic solid. Show your calculation or each
salt. Report the final value in Joules.