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D-7
mark(s) taken off.) Ask your laboratory instructor for help if you are having problems
reading your buret.
Using the automatic dispenser, add 10.00 mL of the NaNO2 solution into the clean glass vial. Using long
tweezers, carefully lower the vial into the Erlenmeyer flask, so that the vial stands upright on the bottom of
the flask. Be careful not to splash out any NaNO2 from the vial into the sulfamic acid, or the reaction will
start prematurely. Carefully stopper the Erlenmeyer flask with a rubber stopper so that the system is
airtight.
For Run 1, set the level of water in the buret to ~ 22 mL. Accurately read the water level in the buret and
record this level on your Observations Sheet where it asks for the initial buret reading for Run 1. To start
the reaction, tilt the flask so that the vial tips over and the sulfamic acid solution enters the vial. Initially,
swirl the flask very gently because you do not want the reaction to progress too rapidly. After the reaction
has proceeded for about one minute, continue to swirl the flask every 2 to 5 seconds to ensure that all of the
sulfamic acid reacts. The reaction is complete when bubbles no longer enter the buret after a gentle
continuous swirl of the flask (about 3 to 4 minutes after the start of the reaction).
Once the reaction is complete, immediately remove the stopper from the Erlenmeyer flask and record the
final temperature of the solution in the Erlenmeyer flask. Record this as t2 on your Observations Sheet.
Record the final water level in the buret (mL). Also, measure the height of the water column remaining
inside the buret. This height is “h” in Figure 2. Record the room temperature to 0.1°C; this temperature
will be used as the temperature of the gas in the buret.
NOTE: Be sure the bulb of the thermometer is dry when determining room temperature.
Flush the Erlenmeyer flask and vial four times with tap water and then rinse twice with deionized water.
Repeat the above procedure for an additional four runs using the volumes of the sulfamic acid solution and
initial buret levels as outlined below. For each run, remember to immediately remove the stopper from the
Erlenmeyer flask and record the final temperature of the solution in the Erlenmeyer flask once the
reaction is complete as well at the final volume in the buret and the height of the water column remaining in
the buret .
Run 2:
Repeat the experiment following the procedure given for Run 1 using ~ 10.xx mL of sulfamic
acid accurately measured. For this run, set the initial level of water in the buret to approximately the 28
mL mark.
