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Unformatted text preview: used to determine the molar heat
of reaction. Dakota State University page 181 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual Observations:
Part I: Scientific Method
Observations: Dakota State University page 182 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual Part II: Specific Heat
Object Final T Initial T ∆T cobject Obserations: Dakota State University page 183 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual Part III: Heat of Reaction
Run Mixing… with… ∆T ∆H Observations: Dakota State University page 184 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual Pre-Lab Questions:
1. Explain the principle of calorimetry that allows us to measure heat changes.
2. Would an insulator have a very high or very low specific heat?
3. We cannot just measure heat of reaction; what other two heats are necessary for this
calculation? Dakota State University page 185 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual Post-Lab Questions:
1. Did you get the correct object in part I? Do you think you should have? Knowing
what you know now, do the observations you made make sense?
2. What do you suppose are the major sources of error in the specific heat and the heat of
reaction experiments? Dakota State University page 186 of 232 Experiment 18: Kinetics General Chemistry I and II Lab Manual Experiment l8: kinetics
Purpose: To determine the rate law of a chemical reaction
Puree: To chop so fine the material becomes liquid-like Background:
See “Using the Pasco System”
Kinetics is the study of reaction rates, that is, how fast reactions occur. In your
first thought, you might not think this sounds terribly exciting, but consider this; if
explosive reactions occurred more slowly, they would not explode. If diamonds
converted to graphite more quickly, you would not want them. If the metabolic rate is
not correct in your body, you could either starve to death while eating very well (if the
rate is too low) or burn up while eating hardly anything at all (if the rate is too high). In
fact, your body has many intricate methods for very carefully controlling the reaction
rates in the metabolic pathways.
For today’s experiment, we will be using an old demonstration reaction called the
“Iodine Clock Reaction.” The net ionic equation for this reaction is
3 IO 3 - (aq) + 8 HSO3 - (aq) à 8 SO 4-2 (aq) + I3 - (aq) + 6 H+ (aq) + H2 O (l)
Starch is added as an indicator because it will form a dark blue complex with I3 - (aq).
The form of the rate law equation is rate=k[IO 3 -(aq)]x [HSO3 -(aq)]y . In this experiment,
we will determine the values of x, y and k.
You will want to use the Pasco colorimeter. Set it up using the standard
procedure. Choose “red” for the color (we are choosing red, because the complex is blue;
this means the complex absorbs most strongly, we expect, in the red wavelength). Set the
graph for “absorbance” versus...
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