Be careful! The scientist was a bit sloppy again when labeling his containers in the acid and base cabinet. Use your knowledge of acids, bases and the pH value to identify the right liquid! 

Materials needed:

  • 4 test tubes with unknown liquids
  • Universal indicator paper with color scale
  • Test tube holder
  • Glass rod


Execution of experiment and task:

  • You discover the following note in the lab journal: “Important: neutralize solution X! (test tube with required amount was already prepared). Check with indicator paper." But next to the beaker of solution X are 3 test tubes. From class, you know neutralizing has something to do with pH, which has a scale from 1 to 14. Next to the beaker is a yellow strip of paper and a color scale numbered from 1 to 14. That must be this indicator paper.
  • Determine the pH value of solution X and the solutions in the test tubes by placing a drop with the glass rod on a piece of indicator paper. Dip the glass rod into a glass of water between each liquid and dry the glass rod with a paper cloth. Record the color and corresponding pH value in the table. Which solutions are acidic, neutral or basic?
  • Puzzle: Which test tube neutralizes solution X?
  • Verification: 

    Pour the content of the selected test tube into the beaker for solution X to check the result and measure the pH value of this solution after stirring with the glass rod. 

    The code is the number on the test tube.


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