Unformatted text preview: ion, bring the calorimeter to the front of the room and select an object. Record the
label of the object, and with the tongs, remove the object and place it in the water in the
calorimeter. Replace the calorimeter lid, and as quickly as you safely can, return to your
desk and put the temperature probe back into the calorimeter. Keep in mind that in this
time, a f w data points may have been collected that are, for all intensive purposes,
meaningless. Don’t let this worry you.
(7) Watch the graph. You want it to look as if you have a straight line for at least two
minutes. As soon as you are convinced that the line is stable, click “stop”.
(8) Remove the object and dry it off. Measure and record the mass of the object.
(9) Write the data points in your notebook. Do not count on being able to save these
tables as they may be accidentally erased.
(10) As soon as your data collection and transcription is completed, return the object to
the front of the room. Empty the water out of the calorimeter but do not dry it. Repeat
steps 5-10 for the remaining objects.
Part III: Calorimetry – Heat of Reaction
We are interested in how much energy is released when we react an acid (HCl) with a
base (NaOH). There is one problem, however; there will also be heat released when we
dilute the HCl and the NaOH, so we will have to measure these “heat of dilutions” so we
can subtract them in our experiment.
Make sure you coffee-cup calorimeter is clean and dry. Get 20.00 mL of distilled
water in a beaker, and 20.00 mL of sodium hydroxide in the calorimeter. Using your
Pasco probe, determine the temperature of the water. Dry off the probe, and determine
the temperature of the sodium hydroxide. Start collecting temperature points with the
probe in the sodium hydroxide, and quickly but carefully (without splashing) pour the
water into the sodium hydroxide. Quickly put the lid on the calorimeter, and measure the Dakota State University page 179 of 232 Experiment 17: Calorimetry General Chemistry I and II Lab Manual temperature change. Swirl carefully (to avoid splashing); continue measuring the
temperature until it is stable, or slightly decreasing.
Pour the sodium hydroxide solution down the drain (with lots of running water).
Clean and dry the coffee cup calorimeter, and dry the beaker. Get 20.00 mL of
hydrochloric acid in the beaker this time, and 20.00 mL of distilled water in the coffee
cup calorimeter. Just as you did before, obtain the temperature of both solutions, being
sure to rinse off the temperature probe and dry it before transferring it from one solution
to another. With the probe in the hydrochloric acid, begin taking data points. Pour the
HCl solution carefully but rapidly (to avoid splashing) into the coffee cup calorimeter.
Cap off the calorimeter. Swirl it and watch the temperature. Continue taking the
temperature until the temperature has leveled off or begins to slightly decrease.
Pour the HCl solution down the drain with lots of water. Clean and dr...
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