Name:__________________________
Date:_________________Period:____
Enthalpy of Reaction Lab
Objective: To use calorimetry to measure the reaction enthalpies of two chemical reactions.
Materials & Equipment:
 Sodium bicarbonate (NaHCO3)
 Acetic acid (HC2H3O2)
 Magnesium metal
 0.5 M Hydrochloric acid (HCl)
 Coffee cup calorimeter (without the lid)
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Thermometer
100-mL graduated cylinder
Electronic balance
Weigh boats (2)
Timer (phone)
Procedures:
PART 1: Sodium Bicarbonate & Acetic Acid
1) Use a graduated cylinder to measure 30.0 mL of vinegar into your coffee cup calorimeter. Place the
thermometer into the solution.
2) Rinse out the graduated cylinder with water twice.
3) Use the electronic balance to measure 2.1 g of sodium bicarbonate on a weigh boat. Record the exact
mass that you measured here: _____________
4) Read the initial temperature of the thermometer and record it in the data table.
5) Add the sodium bicarbonate to the vinegar and begin timing.
6) Gently stir the solution with the thermometer to ensure good mixing.
7) Record the temperature every 30 seconds until a minimum temperature has been reached and the
temperature readings begin to increase.
8) Dispose of the reaction products in the sink. Rinse out your cup twice.
PART 2: Magnesium Metal & Hydrochloric Acid
1) Use a graduated cylinder to measure 30.0 mL of hydrochloric acid solution into your coffee cup
calorimeter. Place the thermometer into the solution.
2) Rinse the graduated cylinder out with water twice.
3) Use the electronic balance to measure 0.10 g of magnesium metal into a weigh boat. Record the exact
mass that you measured here: _____________
4) Read the initial temperature of the thermometer and record it in the data table.
5) Add the magnesium metal to the acid solution and begin timing.
6) Gently stir the solution with the thermometer to ensure good mixing.
7) Record the temperature every 30 seconds until a maximum temperature has been reached and the
temperature readings begin to decrease.
8) Dispose of the reaction products in the sink. Rinse out your cup twice.
Pre-Lab Question:
1) Balance the two reactions that you will see in this lab, shown below.
HC2H3O2 (aq) + NaHCO3 (s) 
Mg (s) +
HCl (aq) 
CO2 (g) +
H2O (l) +
H2 (g) +
NaC2H3O2 (aq)
MgCl2 (aq)
Name:__________________________
Date:_________________Period:____
Temperature Data:
Time
HC2H3O2 + NaHCO3
Mg + HCl
0 min
0 min 30 sec
1 min
1 min 30 sec
2 min
2 min 30 sec
3 min
3 min 30 sec
4 min
4 min 30 sec
5 min
5 min 30 sec
6 min
6 min 30 sec
7 min
7 min 30 sec
8 min
Calculations: Show all of your work for these calculations in the space below. Put a BOX around your final
answer.
1) Calculate the change in temperature for each reaction using the maximum or minimum temperature that
you observed as your final temperature.
HC2H3O2 + NaHCO3
Mg + HCl
2) Calculate the heat gained or lost by the water during each reaction.
HC2H3O2 + NaHCO3
Mg + HCl
Name:__________________________
Date:_________________Period:____
3) Use the equation qrxn = -qwater to solve for the heat released or absorbed by each reaction. Express your
answer in kilojoules.
HC2H3O2 + NaHCO3
Mg + HCl
4) Use the exact masses that you measured to calculate the moles of the solid reactant that you used in each
reaction. In both cases, the solid was the limiting reactant.
HC2H3O2 + NaHCO3
Mg + HCl
5) Use the following equation to calculate the enthalpy change for each reaction: ∆Hrxn =
HC2H3O2 + NaHCO3
qrxn
moles of solid
Mg + HCl
6) Calculate the percent error for each reaction enthalpy change using the actual values for ΔHrxn.
HC2H3O2 + NaHCO3
Mg + HCl
Analysis: Answer the following questions in complete sentences.
1) Classify each reaction in this lab as exothermic or endothermic. Explain your reasoning.
2) What is the biggest source of error in this lab?