220 DIY Science: Illustrated Guide to Home Chemistry Experiments
- In the third foam cup, make up 100 mL of 1 M hydrochloric
acid by adding 8.3 mL of 12 M HCl to 91.7 mL of water.
CUTIOA nS
Add AICd To wATER ANd wAIT
Always add acid to water. Adding water to a concentrated
acid can cause splattering. Diluting acid produces heat.
Because we want concentration to be the only variable, it’s
important to ensure that all three acid solutions are at the
same initial temperature. Make your dilute acid solutions
ahead of time and allow all three cups to cool to room
temperature before proceeding.z
6.eigh one of the antacid tablets to 0.01 g and record its W
mass on line A of Table 12-3.- Place the first foam cup with 4 M hydrochloric acid on
the balance and record the mass to 0.01 g on line B of
Table 12-3. - Measure and record the temperature of the HCl solution
on line C of Table 12-3. - With the cup and its contents still on the balance, drop
the antacid tablet into the cup.
Note the combined mass of the cup, acid, and tablet every
five seconds and record each mass in Table 12-3. (It may
be helpful to have one person watching the clock while
another calls out the mass reading at each 5-second
milestone.)
Continue recording the changing mass until you reach
one minute or until the reaction completes, as evidenced
by the cessation of bubbling.
When the reaction completes, record the final mass of
the cup, water, and tablet on line Q of Table 12-3.
Dispose of the spent solution and rinse out the cup.
Repeat steps 6 through 9, using 2 M hydrochloric acid.
Repeat steps 6 through 9, using 1 M hydrochloric acid.
10.
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15.
oALIpToN ACTIvITIES
If you have time and the required materials, consider
performing these optional activities:- Graph your results for the trials using 4 M, 2 M, and 1
M HCl. Determine whether the reaction rate is linear
over time and whether the concentration of the HCl
affects linearity. - In the first laboratory, we mentioned that a rule of
thumb says that an increase of 10°C in temperature
should approximately double reaction rate. (Did your
experimental data verify or disprove this speculation?)
Repeat this experiment, using 100 mL of 1 M HCl at a
temperature 10°C higher than the temperature of the
acid in your original run. Compare the results to your
data for the 1 M and 2 M HCl at the lower temperature.
dISoALp S :
Neutralize the spent acid solutions with sodium
bicarbonate or another base and flush the neutralized
solutions down the drain with plenty of water.