The experiment utilized a coffee cup calorimeter to measure the enthalpy change during the neutralization reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH). Results indicated that as the concentration of reactants increased, the heat change (δq) also increased, although this behavior deviated from the expected constant enthalpy change per mole. The experiment concluded with a recommendation for improved precision in measurements and further studies to validate the preliminary findings.

1. Experiment 1: Calorimetry
Post lab
Rawan Douar, Albert Campbell, Riley
Richardson, Christopher Cardenas
02/10/17
Instructor: Meng Chen
CHM2046L
Section: 912
Introduction
We determined the change in enthalpy to be negative, which
means energy is sendoff the system and entering the
environments in the form of heat.
Calorimetry is the chemical process which is used to measure
heat in chemical reaction. The apparatus used is the calorimeter.
A coffee cup calorimeter is not technologically advanced but it
is effective in stopping heat transfer between the system and the
atmosphere. Because the cup is open to the air, this is a constant
pressure measurement. Per the first law of thermodynamics, the

2. total energy of an isolated system can neither be created nor
destroyed. In other words, energy is preserved in
chemical reaction.
Calorimeter will consist of two nested Styrofoam coffee cups
and a plastic cover. It will use a temperature sensor armed with
a thermocouple probe. There will be a hole in the plastic cover
of your calorimeter for insertion of the probe. In this
experiment, we are going to study about the redox reactions
with coffee cup and calorimeter.
Hypothesis and Objectives
Using a coffee cup calorimeter, the heat of neutralization of
HCl and NaOH is measured. From this, the enthalpy change for
the neutralization of one mole of HCl can be calculated.
· Introduction to the technique of calorimetry, in which the heat
is evolved or absorbed by a chemical reaction is incidental by
measuring temperature vicissitudes in an insulated reaction
container.
· Reaction involve strong bases and acids will produce more
heat.
Methods
Following are the materials that are used in experiment.
· Coffee cup calorimeter thermometer
· Lid or parafilm
· 10 mL graduated cylinder
· HCL
· NaOH
· Water
· 250 mL beaker
Procedure
1. Set up calorimeter apparatus.
2. Measuring solution temperature before mixing.
3. Adding simultaneously HCl and NaOH to the coffee cup.
4. Measure temperature change after mixing.
5. Calculate enthalpy change.

3. (J. Kotz, P. Treichel, J. Townsend; Chemistry & Chemical
Reactivity 7th ed. 2009)
Obtain 10 ml of cold water and get the temperature, and pour it
into your calorimeter. Then do the same thing for hot water.
After that, measure the final temperature when it reaches
equilibrium. Use the initial and the final temperatures to
measure Ccal. Now gather two 50 mL beakers, one for NaOH,
and one for HCl. Use the 10-mL graduated cylinder and then
add the 3 mL of HCl and 7 mL of water, measure the
temperature and put it into your unfilled calorimeter. Do the
same for NaOH. Then put the thermometer in and measure the
exact last temperature of it.
Clean up, and do the same thing again, but with 5 mL, then 7
mL of the acid and base, to get .5 Mol and .7 Mol. Clean up
your solutions, it is just NaCl and H2O, so you can solution it
down the drain, if you have an extra HCl then neutralize it with
sodium bicarbonate before pouring down the drain. Now
calculate for the ΔHrxn as seen in the Calculations section
Reaction: NaOH + HCl --------- > NaCl + H2O
In this reaction, Sodium hydroxide react with Hydrochloric acid
to produce salt and water. This is an example of neutralization
reaction. The initial temperature, the final temperature and mass
of solution were measured.
Enthalpy:
Heat transfer does not occur instantaneously, so using
calorimeter to determine the enthalpy change requires
measuring the temperature of the calorimeter contents as the
change occurs.
Q = n H
H = Q/n
Result
The results indicated that when the Molar concentration of the
acid-base pair enlarged, the Δq will be also increased. It also
shows that ΔHrxn increased as well, which shouldn't have
happened, because ΔHrxn is the ratio per mole of the enthalpy
of heat, and it should be constant for the same acid-base pairs.

4. The neutralization reaction of hydrochloric acid with sodium
hydroxide is given below:
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) + heat
Experiment Data Information
Trials
0.3 Mol HCL and NaOH
0.5 Mol HCL and NaOH
0.7 Mol HCL and NaOH
C of calorimeter (J/C)
3.21
3.21
3.21
Initial temperature (C)
20.5
20.0
21.5
Final temperature (C)
21.5
25.0
26.5
Heat Change q(J)
-62.67
-230.912
-397.48
ΔHrxn (KJ/mol)
-2.092
-4.6024
-5.678
Calculations:
q cold initial temp: 22.0 (C`), final temperature 29.0 (C`)
q hot initial temp: 35.5 (C`), final temperature 29.0 (C`)
equation: m x C x ΔT
q cold = 10 x 4.18 x 7.0 = 292.88 J
q hot = -271.96 J

5. q calculation = -20.92 J (-qcal = q cold + q hot)
equation: Ccal = (qcal)/ ΔT
Ccal = 3.124
Solve for ΔHrxn
For 0.3 Mol: q solution = 20 g x 4.18 x (23.0-22.0) = 83.68
qrxn = q solution – q calculation
qrxn = -62.76 J
ΔHrxn = qrxn/0.3 = 2.092 KJ/mol
Decision
Ideally, calorimeters should have an infinitely low lining from
the reaction cavity, and infinitely high insulation on the outside
to ensure that all the heat is transferred to the water, and that
none leaks from the calorimeter itself. The numbers that the
experiment produced show that there is a difference in the heat
transferred dependent on the forte of the acid and/or base and
the possessions of the metal. Although, further experiments
might reveal more conclusive data on the nature of such an
assumption. However, the strongest acid and strongest base
appeared to have the most enthalpy change.
Conclusion
The results fail to invalidate hypothesis, but do not offer
convincing results to uphold hypothesis well e.g. average heat
evolved by the reaction of neutralization.
Not having the precise mass of solutions (when poured from
beaker to Styrofoam cup)
Inexact quantities of reactants (due to lack of usage of
volumetric measuring instruments)
Research Connection
Graphite calorimeters used in radiotherapy for cancer. The
radiation therapy conveys heat and this heat is measured using
the isothermal sensors in the graphite calorimeter. The
reasoning behind this is so that excess radiation does not kill
healthy tissue.

6. References
· http://web.lemoyne.edu/giunta/chm151L/calorimetry.html
· J. Kotz, P. Treichel, J. Townsend; Chemistry & Chemical
Reactivity 7th ed. Instructors Edition; Brooks/Cole; 2009
· Gary L. Bertrand, retrieved from
https://web.mst.edu/~gbert/cupCal/disc.htm