Illustrated Guide to Home Chemistry Experiments

Chapter 12 Laboratory: Chemical Kinetics 213

CUTIOA nS

Although the chemicals used in this laboratory are not

hazardous, it is good practice to wear splash goggles,

gloves, and protective clothing at all times.

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SBSTITUTIU oNS ANd modIfICATIoNS

• You may substitute any brand of fizzy tablets for the
  Alka-Seltzer tablets.


• If you don’t have Alka-Seltzer or similar tablets, you may
  substitute small sticks of chalk or calcium carbonate
  antacid tablets for the Alka-Seltzer tablets and cold and
  warm dilute (~3 M) solutions of hydrochloric acid for the
  water. If you do that, remember that hydrochloric acid is
  corrosive and hazardous to handle.

POCEDURER
1.f you have not already done so, put on your splash I
goggles, gloves, and protective clothing.

2. Weigh one of the tablets to 0.01 g and record its mass on
   line A of Table 12-1.


3. Add about 100 mL of cold tap water to the foam cup.
   (Use a foam cup rather than a beaker to keep the
   mass of the reaction vessel and its contents under the
   maximum capacity of your balance. If the combined
   mass of the foam cup, Alka-Seltzer tablet, and 100 mL
   of water is greater than the maximum capacity of your
   balance, reduce the quantity of water accordingly.)


4. Weigh the foam cup and water and record the mass on
   line B of Table 12-1.


5. Measure and record the temperature of the water on
   line C of Table 12-1.


6. With the cup and water still on the balance, drop the
   tablet into the cup.


7. Note the combined mass of the cup, water, and tablet
   every five seconds and record each mass in Table 12-1.
   (It may be helpful to have one person watching the
   clock while another calls out the mass reading at each
   5-second milestone.)


8. Continue recording the changing mass until you reach
   one minute or until the reaction completes, as evidenced
   by the cessation of bubbling.


9. When the reaction completes, record the final mass of
   the cup, water, and tablet on line Q of Table 12-1.
   Dispose of the spent solution and rinse out the cup.
   Repeat steps 1 through 9, using hot tap water.
   Repeat steps 1 through 9, using a mixture of half hot and
   half cold tap water.

10.

11.

12.

dISpoSAL: All of the solutions from this laboratory can

be flushed down the drain with plenty of water.

FIGURE 12-1: Observing the mass change as the Alka-Seltzer

tablet reacts and carbon dioxide is evolved