Sample Presentation
IB Chemistry III
Andrea Carver
 D.2.1
State and explain how excess acidity in
the stomach can be reduced by the use of
different bases.
Presentations should
include list of objectives
for topic.
 The
pH along the length of the
gastrointestinal system must be controlled.
 Digestive enzymes work best at unique
optimum pH’s. (Pepsin in stomach.)
 The stomach maintains an acidic pH 1-2 via
production of HCL .
 Acidic environment also kills bacteria.
Presentations should include
summary of content from
textbook.
 Can
be caused by alcohol, smoking, stress,
anti-inflammatory drugs.
 Possible outcomes:



Acid Indigestion
Heartburn
Ulcer
Presentations should include
images which help clarify
concepts.
 Antacids
are weak bases which neutralize
excess stomach acid (HCL).
 Examples:




Metal Oxides
Metal Hydroxides
Carbonates
Hydrogen Carbonates
 The
reaction of a strong acid with a weak
base yields a salt and water. (The acid is
neutralized.)
 Magnesium
hydroxide and aluminum
hydroxide can act as antacids.



Write an equation for the reaction of HCL with
each of these antacids.
Identify which antacid neutralizes the greater
amount of acid if 0.1 mol of each antacid is used.
Suggest why potassium hydroxide is not used as
an antacid.
Presentation should include an exercise
from the textbook or practice packet.
 Al(OH)3+
3HClAlCl3 + 3H2O
 Mg(OH)2+ 2HCl MgCl2+ 2H2O

Based upon the balanced chemical reaction,
1 mol of Al(OH)3 will neutralize 3 mols of
HCl. So .1 mol Al(OH)3 will neutralize .3
mols of HCl. .1 mol MgCl2 will only
neutralize .2 mol HCl.
 Potassium
hydroxide is a strong base and
would be corrosive to the GI system.
 The
reaction of carbonates and
hydrocarbonates with a strong acid will
produce a salt, water, and carbon dioxide.
 Example:

CaCO3 + 2HCl  NaCl + H2O + CO2
 The
carbon dioxide gas may cause bloating
and flatulence.
 Antifoaming agents (such as dimethicone) are
used to overcome this side effect.
 Antacids may also contain alginates which
prevent reflux.
 How
can bases reduce excess acidity in the
stomach?
 Via Neutralization Reactions!
 Weak bases can react with excess HCl in the
stomach producing salt, water, and
sometimes CO2. In this way, excess acid is
neutralized, and stomach pH will be reduced
to normal levels.
Presentation should include standards addressed as questions.
Answers should be clear and concise.
 You
should be prepared to provide answers
and assist students with all problems on your
topic from Medicines and Drugs practice
packet.