Acid Base Indicator Report Format 26525z

CHEM 321 Evaluation of Acid-Base Indicators Report Name: Lab Partner: Experiment Date: Report Due Date: *When typing your report, please 1.5 or 2.0 space your text. to submit your report to Safe Assign and turn in a hard copy to your instructor. The hard copy may be printed on both sides of the paper. *When you write a report, please remove all questions/text that we have included to guide your responses. You may leave the questions at the end in the report. You may need to reformat your tables to fit your data. Do not treat this as a “fill in” worksheet – it should appear like a formal lab report when printed out. Abstract In one paragraph, summarize the results of your experiment. Include all pertinent information as described in earlier reports.

 

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I. Data and Results  

Table 1. Titration of Tris and HCl using Bromothymol Blue (BB) Tris  (g)   Vinitial  (mL)   Vfinal  (mL)   Vtotal  (mL)   Titrations   (±  0.0002)   (±0.05)   (±0.05)   (±0.07)   Scout          

 

Color  Change    

 

HCl  (M)    

 

NA  

1  

 

 

 

 

 

 

 

 

 

 

 

 

 

Discuss the data in Table 1.

Table 2. Titration of Tris and HCl using Methyl Red (MR)

 

 

Tris  (g)  

Vinitial  (mL)  

Vfinal  (mL)  

Vtotal  (mL)  

Scout  

(±  0.0002)    

(±0.05)    

(±0.05)    

(±0.07)    

1  

 

 

 

 

 

 

 

 

 

 

 

 

 

Titrations  

Color  Change    

 

HCl  (M)    

 

NA  

Discuss the data in Table 2.

Table 3. Titration of Tris and HCl using Bromocresol green (BG) Titrations  

Tris  (g)  

 

Vinitial  (mL)   Vfinal  (mL)   Vtotal  (mL)  

 

Color  Change    

HCl  (M)  

Scout  

(±  0.0002)      

(±0.05)      

(±0.05)      

(±0.07)      

       

 

1  

   

   

   

   

   

 

 

   

   

   

   

   

 

NA  

Discuss the data in Table 3.

 

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  Table 4. Titration of Tris and HCl using Methyl Orange (MO) Tris  (g)   Vinitial  (mL)   Vfinal  (mL)   Vtotal  (mL)   Color  Change   Titrations   (±  0.0002)   (±0.05)   (±0.05)   (±0.07)         Scout                      

 

HCl  (M)     NA  

1  

   

   

   

   

   

 

 

   

   

   

   

   

 

Discuss the data in Table 4.

II. Results and Conclusions Briefly summarize your results and describe your conclusions. Include specific results for each part of the experiment. This section should include everything that appears in your abstract as well as a thoughtful analysis of the experiment. In your analysis of the experiment, address the following: 1. Which indicator is best for standardizing HCl? Explain. 2. Write out the reaction taking place and draw chemical structures. Describe the reaction under consideration. 3. Do your experimental results agree with what you predicted before the lab? 4. Describe your pre-lab predictions for the experiment and explain why the results can be determined without performing the actual experiment. 5. Draw the chemical structures of all the indicators used and incorporate into your discussion. 6. Explain why you should never use more than a few drops of indicator and why the number of drops you use should be consistent over the course of your experiment.

 

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III. Questions 1. Based on the results of this experiment, what indicator would you use for an experiment using Tris and nitric acid? 2. Consider a titration curve for a weak base and a strong acid. Suppose both phenolphthalein and bromocresol green are present in the solution. What color changes would occur at pH 10, pH 7, and pH 3? 3. Students measured the concentration of HCl in a solution by various titrations in which different indicators were used to find the end point. Indicator

Mean HCl (M) ± StdDev

Number of Measurements

1. Bromothymol Blue

0.09565 ± 0.00225

28

2. Bromocresol Green

0.08641 ± 0.00113

18

3. Methyl Red

0.08686 ± 0.00098

29

Is the difference between indicators significant at the 95% confidence level? a. Compare indicators 1 and 2. b. Compare indicators 2 and 3. c. Compare indicators 1 and 3. d. Relate these results back to your experimental findings.

IV. Calculations You may hand-write or scan your notebook calculations. Please include calculations even if you submitted them on your data sheet.

V. References Please use Journal of the American Chemical Society format.

 

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