Acid and Base Lab with Report

Day 1: After completing the pH Gizmo and preparing red cabbage indicator solution, students were formally introduced to acids and bases via a lab.  Having just learned about indicators (chemical solutions that change color in response to changes in pH, Lesson 117) we reviewed Day 1 of the Acid and Base Lab Report Packet. and then students had the remainder of the day to work through the Day 1 worksheet and prepare for the lab.


Day 2: For Day 2 of the Acid and Base Lab, students used their red cabbage juice indicator solution to measure the pH of eight different solutions (comparing the color of the indicator to a color chart for red cabbage indicator). Students repeated the process using universal indicator.  Finally, students evaluated the effect of sodium bicarbonate (baking soda) on the pH of the solutions, as determined by the indicator colors.  Students should carefully document all steps of the lab, taking pictures of the indicator solutions before and after addition of sodium bicarbonate.  Indicator Solution Charts are provided below:

Universal Indicator Chart
Universal Indicator Chart

 

Red cabbage indicator chart
Red cabbage indicator chart

Days 3+: Students will work with their assigned lab groups to write a lab report for the Acid and Base Lab.  The lab report will consist of:

  • Introduction – a paragraph explaining the purpose of the lab
  • Safety Concerns – list all safety concerns associated with working with acids and bases, along with required precautions for the lab (explain why each piece of personal protective equipment is required)
  • Procedure – an ordered list of steps explaining:
    • how the red cabbage indicator solution was prepared
    • pH evaluation of all samples in universal indicator and red cabbage juice indicator solutions
    • pH evaluation of all samples after calcium carbonate added
    • pH measurement with pH probe
  • Resultsdata table with all results, pictures of all results, and one paragraph each of the outcomes of:
    • pH determined with red cabbage indicator solution
    • pH determined with universal indicator solution
    • pH determined with pH probe
    • pH determined after addition of calcium carbonate
  • Conclusions – one paragraph each explaining:
    • The effectiveness and consistency of indicator solutions, relative to the two indicator solutions compared with the pH probe
    • An explanation of how calcium carbonate affected pH
    • Bonus: An explanation of why the indicator solutions changed color (with sources cited)
    • Bonus: An explanation of why calcium carbonate affected pH (with sources cited)
  • Sources (if necessary)

Day 4: After a much-need 4-day weekend, we began class with the Lesson 84 PowerPoint which included a starter question helping students connect acid/base chemistry with the biology of heartburn.  For the lab last week, students observed the effect of sodium bicarbonate (NaHCO3, or baking soda) on acids and bases.  For the ChemCatalyst, students made the connection of acid neutralization with the related compound calcium carbonate (CaCO3, commonly found in antacids).  Students have the remainder of the short week to complete the lab report from the lab last week.  The group lab report packet is due at the end of school Friday, and the lab report must be shared with the teacher by midnight Friday.  Late work will receive a maximum of 60% credit.

Groups who finished early will be provided with a variety of learning enrichment options related to our work thus far during the unit, including:

  • Evaluate absorbance and %transmission with a spectrophotometer, then create and analyze a graph
  • Analyze the spectra of atoms and stars via Gizmos
  • Evaluate waves with an oscilloscope, then create a how-to video or pamphlet

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