Chemistry 101
Name:_________________________
REPORT FORM
Data Table
Parameter
Reaction 1
Reaction 2
Reaction 3
NA
Mass of NaOH (g)
Initial temperature (°C)
Final temperature (°C)
CALCULATIONS TABLE
Mass of R’xn
mixture (g)
Rx’n #
ΔT (°C)
Total heat released
(kJ)
Moles of NaOH
Heat released per
mol of NaOH (kJ/mol)
1
2
3
Conclusions:
Complete the table below by writing a balanced net ionic equation for each part of this experiment with the
corresponding enthalpy change ( H)
Rxn
1
2
3
Balanced Net Ionic Equation
H
(kJ/mol)
Calculations:
1. Determine the change in temperature, ΔT, for each reaction. Record your results in the results
table in Step 15.
2. Calculate the mass of the reaction mixture in each reaction. (To do this, first determine the
total volume of the solution. Then calculate the mass of the solution, based on the assumption
that the added solid does not change the volume and that the density of the solution is the same
as that of pure water, 1.0 g/mL.) Remember to add the mass of the solid to the mass of
solution in Reactions 1 & 2. Record your results in the calculations table.
3. Calculate the total heat released in each reaction, in J, assuming that the specific heat capacity
of the solution is the same as that of pure water, 4.184 J/g°C. Record the result in the
calculations table. (Remember: heat of reaction = m x C x ΔT)
4. Calculate the number of moles of NaOH used in reactions 1 and 2 where n = m/MW. Record
the results in the calculations table.
5. Calculate the number of moles of NaOH used in reaction 3 by multiplying the volume of NaOH
times the molarity (1.000 mol/L). Record the results in the calculations table.
6. Calculate the enthalpy change, in kJ/mol, of NaOH for each reaction and record the results in
the calculations table. (Show calculations for each reaction in the spaces below or attach
additional pages; Round answers to 3 sig figs)
Reaction 1
Reaction 2
Reaction 3
Questions:
1. Show that the equations for reactions 1 and 3 add up to equal the equation for reaction 2.
Include the energy released per mole of NaOH in each equation. Use this information to discuss
Hess’s Law as it relates to this experiment.
2. Calculate the percent difference between the heat given off in reaction 2 and the sum of the
heats given off in reactions 1 and 3. Assume that the heat given off in reaction 2 is correct.
% Difference =
H 2 -( H1 + H3
x100 =
H2
3. Answer the following questions in regards to part 3 of this experiment, by choosing the appropriate
response:
a) How would your values for heat of the reaction change if you used 200.0 mL of each reagent
instead of 100.0 mL?
Increases
Decreases
Does not change
b) How would your values for enthalpy of the reaction change if you used 200.0 mL of each
reagent instead of 100.0 mL.
Increases
Decreases
Does not change
Be sure to save a copy of your eLab Notebook and submit with your report form when completed.