Plop! Plop! Fizz! Fizz!
Oh, the things chemistry teachers
can do with AlkaSeltzer!
Patricia Mason, PAEMST 2003
Delphi Community High School
masonp@delphi.k12.in.us
Judith Flint Baumwirt
Granada Hills Charter High School
jbaumwirt@ghchs.com
July 2005, ChemEd Conference, UBC, Vancouver, Canada
Experiments and Activities
Alka Seltzer Rainbow - ChemFax
Demonstration (provided by Flinn Scientific)
 Alka Seltzer Rockets
 Buffering Ability of Alka Seltzer Tablets
 Buffer Balancing Acts - ChemFax
Demonstration (provided by Flinn Scientific)
 Common Ion Effect on the Solubility of
Alka Seltzer

Experiments and Activities
Change in pH and Temperature as a
Reaction Occurs
 Differentiating Liquids
 Decomposition of Effervescent Tablets
 Decomposition of Effervescent Tablets
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with Sample Data Analysis/Results
Density Challenge
 Does a Gas Have Mass?
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Experiments and Activities
Effect of Particle Size on Rate of Reaction
Demonstration
 Effect of pH on rate of reaction
 Effect of Temperature on Rate of
Reaction Demonstration
 Rate of Reaction Lab - Combined
Activities for Students
 Equilibrium and Rate Determining Step
demonstrations

Experiments and Activities
Micro Popper (provided by Flinn Scientific)
 Quantitative Determination of Sodium
Bicarbonate in Alka Seltzer
 Second Quarter Laboratory
Evaluation: Analysis of Alka Seltzer
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(provided by Flinn Scientific)
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What Chemists Do: Identification and
Analysis - White Powder Identification
Alka-Seltzer Rockets
Factors affecting the rates of solution
 It is important to break tablets evenly into
four quarters
 Only Fuji canisters provide a good seal
(lid fits securely inside the canister)
 Inverted in the launcher
 Can be used test variables

Factors Affecting Rate of Reaction

Effect of
Temperature on Rate
of Reaction
 Teacher
demonstration
 Student activity
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Effect of Particle
Size on Rate of
Reaction
Whole tablet
Broken in half
Quartered
Coarsely ground
Finely ground
Effect of pH on Rate of Reaction
Complicated set-up
 Glass work done by teacher saves time
 Solutions available of various pH
 Each group uses water plus 2 others
 Water displacement technique
 Plotting data and analysis
 Comparison of rates with pH

Common Ion Effect
Can be used as a discrepant event
 Why do the tablets dissolve at different
rates and in varying amounts?

Monitoring Changes in pH and
Temperature as Reaction Occurs

Must use probeware
for pH
 Temperature
 Tablets are added to
room temperature
water
 Data taken for 5
minutes
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Variables can be
changed
Number of tablets
Division of tablets
Amount of water
Amount of agitation
Buffering Ability of Alka-Seltzer
Tablets
Macro-Demonstration
 Burets HCl and NaOH
 Universal indicator
 HCl with water
 HCl with tablet
 NaOH with tablet
 NaOH with water
 Can also use pH
probes
Micro-Activity
 Broken tablets
(0.15g to 0.20 g
samples)
 Well-plates
 Universal indicator
 Calibrate the micropipettes for drops
Does a Gas Have Mass?
Can be used initially for introduction to
Chemistry
 Can be used to demonstrate
conservation of mass
 When a gas is produced is mass lost?
 Baggie provides a closed system

Differentiating Liquids Lab
Good introductory lab activity
 Properties of Liquids
 Viscosity
 Density
 Solubility
 Detailed data recording and evaluation
 Inquiry section, if time permits

Equilibrium and Rate
Determining Step Demo
An entertaining student-centered activity
 Shows the progress of a reaction from
reactants to a mixture of reactants and
products
 Can visually recognize that the reaction
is favored in the decompositon direction
 The “Slow step” is obvious in this
demonstration

What Chemists Do – A Beginning
Analysis Lab
This is a good application of inquiry and
the scientific method.
 May be useful as a beginning lab on
analysis
 Students have three unknowns to
determine so the lab requires some
extended prep time.

Quantitative Determination of
Sodium Bicarbonate
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AP Chemistry
Stoichiometry
Calculations
Limiting Reactant
Graphing
Acid-base
Solutions
Decomposition