Current Lab Report

The pH Scale

 

In this lab, you will use blue and red litmus paper to identify acidic and basic substances.  Blue litmus paper will turn red under acidic conditions, and red litmus paper will turn blue under basic conditions.  Neutral substances do not change the color of red or blue litmus paper.

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This is a Lab Report assignment – each student must write and complete the following segments listed on a separate piece of paper.

 

Problem Statement: You will use the following Problem Statement: “Do substances that appear similar have similar pH values?”

Hypothesis: Create your own hypothesis to answer the Problem Statement.  Remember that your hypothesis must be an “if-then” statement.

Materials: Use the list of materials provided below in the Materials section.

Procedure: Use the procedure given below in the Procedure section.

Data: Copy and complete the data table shown in the Data section.

Results: Evaluate your data from your Data section.  In one paragraph, express and describe your data in sentence form.  Make sure to describe any similarities or differences you may have seen in more detail than the data table gives your reader.

Conclusion: In one paragraph, state whether or not your hypothesis was supported by your experiment.  Restate the overall conclusion you arrived at from answering your problem statement.  Discuss any areas where you feel you may have made mistakes, and suggest where you may be able to make corrections if you were to repeat this lab.

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Materials

Glass stirring rod

Litmus paper, red and blue (at least 4 strips each)

Paper towels

Plastic cup

Test substances (6) in test tubes

Watch glass

Water

Safety equipment: lab apron, safety goggles

 

Procedure

  1. Obtain samples of six test substances from your teacher.
  2. Place one piece of red litmus paper and one piece of blue litmus paper on a clean watch glass
  3. Test the pH of a substance by dipping a glass stirring rod into it and then touching the stirring rod to the piece of blue litmus paper; repeat this step for the red paper.  Place only one drop of each substance on the litmus paper so that the litmus paper may be used for multiple tests.
  4. Make sure to wash your glass stirring rod in between tests to prevent cross-contamination.  Repeat step 3 for the other seven substances. 
  5. Observe any color changes in the litmus paper, and record your observations in the table below.

 

 

Data

Substance

Qualitative Observations (color, etc.)

Effects on Blue Litmus Paper

Effects on Red Litmus Paper

Acid, Base, or Neutral

1

 

 

 

 

2

 

 

 

 

3

 

 

 

 

4

 

 

 

 

5

 

 

 

 

6