Antacid Effectiveness -- April, 2002
Teacher Hints:
- Except for the probe tip, avoid getting the
sensor, interface, or computer wet. Use extra caution with acid
solutions near computers!
- Hydrochloric acid solution: 100 mL per group
will be needed for each antacid brand the group will test. Based
on the number of lab groups, dilute enough stock solution ahead
of time to have plenty of 0.1 M solution on hand. Remind students
of basic cautions to observe when working with acids. Dispose
of excess acid properly: remember to neutralize waste HCl with
sodium bicarbonate solution or a similar base before flushing
down the drain with large amounts of water.
- In this experiment students are analyzing the
rate of change in pH, not measuring the actual amount of stomach
acid neutralized. One possible extension to this experiment would
be a titration with a comparable base (i.e., 0.1 M NaOH) to determine
the actual volume of acid neutralized.
- Based on the active ingredient(s) in the antacid
tablets you have chosen to work with, have students write the
correct balanced reaction for the neutralization reaction in question.
You can find sample reactions for common antacid ingredients at
this link: http://www.chem.latech.edu/~deddy/chem104/104Antacid.htm
- As time permits for additional trials,
challenge students to do a comparative analysis of the effectiveness
of different brands of antacids, which can include background
research into the active ingredients of popular products. Alternatively,
assign different lab groups varying antacid brands to analyze,
and compare the final results obtained throughout the class.Remember
safety is first.
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