Exothermic Stopping Mechanism Utilizing Sulfuric Acid
Chemical Engineering Car
Tara.e.smith@asu.edu
Arizona State University: CHE 494
January 11, 2009
The purpose of this experiment was to find a cost-effective reaction to produce a minimum temperature
of 38⁰C. The temperature was recorded at various molarities by adding sulfuric acid (H2SO4) to water.
The theoretical temperature can be determined by using the heat of solution, -71.76 KJ/mol.
Introduction
Experimental
The heat of solution is the energy produced by
the dissolution of a solute. Since strong acids
readily dissociate into their common ions the
literature value is readily available. For sulfuric
acid the heat of solution is -71.76 KJ/mol. The
heat of solution can be calculated via the
following equation where the specific heat is of
the solvent.
To determine the temperature of the
dissociation of the acid. Under the laboratory’s
hood various milliliters of sulfuric acid starting
from 1 mL was added to 20 grams of water in a
50 mL beaker. The solution was continuously
stirred via a stir rod. The mixture values can be
found in table 1. The temperature was
recorded with a thermometer. This allows the
theoretical and experimental temperatures to
be compared.
∆H= heat energy (q)/mol solute =
(mass)(specific heat)(change of temperature)
This allows the final temperature of the solution
to be calculated. By manipulating the
quantities of chemicals the ideal temperature
can be reached while minimizing excess. This
helps minimize the costs associated with the
stopping mechanism.
Materials





50 mL beaker
Graduated cylinder
Stir rod
Distilled water
Sulfuric acid
Furthermore, to test the influence of the
solvent the experiment was repeated with 50
grams and 100 grams of water as seen in tables
two and three.
Also, once the known concentration is found by
the observed values that exact trail was
repeated and timed to determine the speed of
dissolution.
Table 1: Sulfuric acid into 20 g water
mL of
H2SO4
moles
0
0
1 0.01876
2 0.03752
3 0.056281
4 0.075041
5 0.093801
Calculated K
296.15
312.2378543
328.3257086
344.4135629
360.5014172
376.5892715
C
F
Observed
23
39.08785
55.17571
71.26356
87.35142
103.4393
73.4
102.3581
131.3163
160.2744
189.2326
218.1907
Table 2: Sulfuric Acid into 50 g water
mL of H2SO4
moles
0
0
1 0.01876
2 0.03752
3 0.056281
4 0.075041
5 0.093801
Calculated K
296.15
302.5851417
309.0202834
315.4554252
321.8905669
328.3257086
C
F
23
29.43514
35.87028
42.30543
48.74057
55.17571
73.4
84.98326
96.56651
108.1498
119.733
131.3163
C
F
23
29.43514
35.87028
42.30543
48.74057
55.17571
73.4
84.98326
96.56651
108.1498
119.733
131.3163
Observed
Table 3: Sulfuric Acid into 80 g water
mL of H2SO4
moles
0
0
1 0.01876
2 0.03752
3 0.056281
4 0.075041
5 0.093801
Calculated K
296.15
302.5851417
309.0202834
315.4554252
321.8905669
328.3257086
Observed