Alka-Seltzer Lab

Purpose:

You work for Safeway Inc. and are testing the quality of the effervescent tablet that is sold as an alternative to Alka-seltzer. You want to make sure that the tablet delivers as much relief as possible and you can measure this by measuring the amount of bubbling. You will predict the amount of bubbling theoretically possible and compare it to the actual amount of bubbling.

The reaction that occurs is: NaHCO3 + HC6H7O7 --> NaC6H7O7 + CO2 + H2O

HC6H7O7 = Citric Acid

Hypothesis:

• Predict the amount of CO2
• Don't forget to consider which reactant is limiting…show all your calculations to justify your prediction
• Hypothesis should use the words theoretical yield and limiting reactant

Materials:

• Safeway brand Effervescent Tablets
• You need to determine the rest...

Procedures:

• One detail that I'm giving you… You will be dissolving the tablet in 100 mL of water in a 150 mL beaker
• You work out the details...

Data:

• Don't forget to include data from the package…
• Theoretical yield, actual yield and percent yield

Analysis:

• Calculate the amount of CO2 given off (actual yield) and percent yield.
• Calculate volume at STP
• Show all calculations and units

Error Analysis:

• Did you get alot more CO2 than you thought? Here is one possible error you need to discuss:
  • Citric Acid was not a reactant and therefore did not directly control the amount CO2 made
  • The reaction occurring could be: NaHCO3 --> CO2 + NaOH
  • The citric acid is used to neutralize the base (NaOH) formed so that it doesn't upset your stomach
• You should calculate a new theoretical yield based on the amount of NaHCO3
• Then calculate a new percent yield (hopefully it will be less than 100%...)
• Describe other sources of error that could be factors

Conclusion:

• Standard conclusion - use template if necessary