h. Save the activity. Select a file name with less than 10 characters and devoid of punctuation. 3. CALORIMETER SET UP Obtain two styrofoam cups and a lid from the TA. Place one styrofoam cup inside the other. Place a stir bar in the cup. Set the apparatus on a stir plate placed next to the metal support rod on the bench top as shown in Figure 6.3. Using a clamp, fix the temperature sensor suspended in the styrofoam cup without touching the base of the cup or the stir bar.
6-9 4. DATA COLLECTION – NaOH solid in water (Reaction 1). a. Using a graduated cylinder, add 50.0 mL of distilled water to the calorimeter and record its volume. Place the temperature sensor into the calorimeter such that the tip is submerged and adjust the stir plate to a slow speed. b. Weigh out about 2 grams of sodium hydroxide, NaOH, by difference and record the mass to the nearest 0.001 g. Note: Since sodium hydroxide absorbs moisture from the air, weigh this substance by difference, using a stoppered 125-mL Erlenmeyer flask as a weighing bottle. Handle the NaOH and resulting solution with care – DO NOT touch with bare hands. Be sure to clean up any spilled NaOH(s) because it absorbs water from the air and forms a solution that is very corrosive. c. When the calorimeter is assembled and the NaOH sample is ready, click START in the top menu bar above the experimental setup window. Take time-temperature readings for 3 minutes. d. After the initial 3 minute interval, add the solid sodium hydroxide to the calorimeter and record the time of mixing in your lab notebook. Continue to record time-temperature readings for a total of 10 minutes. e. Click STOP when completed. Rename the data set.
6-10 f. Remove the stir bar and empty the contents of the calorimeter into the sink. Rinse the Styrofoam cup and temperature sensor with distilled water. Be careful not to lose the stir bar. Reassemble the calorimeter. g. Repeat steps a-f to obtain a second trial for this reaction. h. Save Activity after each reaction. 7. DATA COLLECTION – NaOH and HCl solutions (Reaction 2). a. Using a graduated cylinder, add 50.0 mL of 1.0 M HCl to the Styrofoam cup and record its volume in your lab notebook. Adjust the stir plate to a moderate speed and reassemble the calorimeter with lid and temperature sensor in place. b. Measure 50 mL of 1.0 M NaOH into a clean graduated cylinder and record its volume in your lab notebook. c. Before adding the NaOH to the calorimeter, click START. Collect time- temperature readings for the 1.0 M HCl solution for 3 minutes . d. Add the NaOH solution to the calorimeter and record the time of mixing in your lab notebook. Continue taking time-temperature readings for a total of 10 minutes. e. Click STOP when completed. Rename the data set. f. Remove the stir bar and empty the contents of the calorimeter into the sink. Rinse the Styrofoam cup and temperature sensor with distilled water. Reassemble the calorimeter for the next reaction.
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