Strong acid Strong base

Edit Experiment

VIDEO LINKS:

Lab Experiments (Write protocols and perform experiments based on these):

  1. Making the 0.10 M NaOH solution:
  2. Calibrating the pH probe:
  3. Titrating the 0.10 M HCl solution with the 0.10 M NaOH solution:
  4. Preparing the burette

Data analysis and calculations (Use these if you need help with your data and calculations)

  1. Strong acid and strong base titration calculations
  2. Finding the equivalence points
  3. pH curves
  4. Dilutions of solutions

The prelab must include Experimental Protocol, Chemical Table and Equipment Table.

The lab report requires all sections (including prelab sections) to be completed in one document.

Experimental Protocol

  1. (Analysis) Watch the experiment videos. Take notes on the protocol.  Stop the video and re-watch as necessary to acquire the details of the procedure.  Write out the protocol for each part of the experiment.  (It can be written in sequential steps.  Complete sentences are not necessary.)  This is the protocol you will follow, so be detailed.
  2. Create flow charts with detailed instructions for making the following solutions:
    1. Making the 0.025 M NaOH solution by dilution from 0.1M NaOH:
    2. Preparing the 0.10 M HCl solution from 1M HCl:
    3. Preparing the 0.05 M HCl solution by dilution from 0.1M HCl:
  1. (Manipulation) Assume that you have are titrating 15.0 mL of the 0.1 M HCl solution with the approximately 0.1 M NaOH solution with the concentration determined by the standardization with KHP. Calculate the volume of required NaOH solution to reach the equivalence point in this titration.
  2. (Manipulation) Assume that you have are titrating 15.0 mL of the 0.05 M HCl solution with the NaOH solution with the concentration determined by the standardization with KHP for the approximately 0.025 M NaOH solution. Calculate the volume of required NaOH solution to reach the equivalence point in this titration.

Chemical Table

(Representation) Prepare your chemical table including the materials you will use in the experiment.  Here is a general template that you may use.
Chemical Name Chemical Formula Molar Mass (g/mol) Hazards Reference PPE
Sodium Chloride NaCl 58.5 Skin irritation https://fscimage.fishersci.com/msds/21105.htm  
           
           

Equipment Table

(Analysis) Identify the equipment (type AND size) needed for the experiment and include the name and an image of each.  Be sure to describe the equipment, how to use it, and why it is suitable for this use.
Equipment Name Equipment Picture Intended Purpose

Data Collection

(Acquiring competencies) Following your detailed protocol based on the videos, perform all the experiments. Record your observations and take pictures of your key steps in the process.  Your observations and images need to be incorporated in your data section and this section should be as detailed as possible as you will use this information to complete your discussion.

Data Processing

Part 1: Titrating HCl solutions with NaOH

  1. (Acquiring competencies) Following your detailed protocol based on the videos. Filling your burette with the NaOH solution, perform the titration of the 0.1 M HCl with 0.1 M NaOH once, and then repeat it with the 0.050 M HCl and the 0.025 M NaOH. Record your observations.
Titration A Approximate [NaOH] Approximate [HCl] Volume of HCl solution (mL)
1 0.1 M 0.1 M 15
2 0.025 M 0.05 M 15
 
  1. (Acquiring competencies) Following your detailed protocol based on the videos. Filling your burette with the HCl solution, perform the titration of the 0.1 M HCl and 0.1 M NaOH once, and then repeat it with 0.050 M HCl and 0.025 M NaOH. Record your observations.
Titration B Approximate [NaOH] Approximate [HCl] Volume of NaOH solution (mL)
1 0.1 M 0.1 M 15
2 0.025 M 0.05 M 15
 
  1. (Representation) Write the balanced chemical equation for this experiment.
  2. (Representation) Write the balanced complete ionic equation for this experiment.
  3. (Representation) Write the balanced net ionic equation for this experiment.
  4. (Analysis) Classify the observed reaction.
  5. (Manipulation) Calculate the moles of HCl in 15 mL of a 0.1 M HCl solution.
  6. (Manipulation) Using the actual volumes of NaOH and HCl solutions from your titration and the concentration of the approximately 0.1 M NaOH solution determined by the standardization with KHP, calculate the actual concentration of the 0.1 M HCl solution.
  7. (Manipulation) Calculate the moles of HCl in 15 mL of a 0.05 M HCl solution.
  8. (Manipulation) Using the actual volumes of NaOH and HCl solutions from your titration and the concentration of the approximately 0.025 M NaOH solution determined by the standardization with KHP, calculate the actual concentration of the 0.05 M HCl solution.
  9. (Manipulation) Calculate the concentration of the H3O+ and determine the pH in 15 mL of a 0.1 M and the 15 mL of 0.05 M HCl solutions.
  10. (Representation) Draw the pH curves for each experiment from Titration A. (pH on the y-axis and mL NaOH added on the x-axis)
  11. (Representation) Draw the pH curves for each experiment from Titration B. (pH on the y-axis and mL HCl added on the x-axis)
  12. (Interpretation) Find the equivalence point of your titration for each experiment from your graphs.
  13. (Interpretation) Find the pH at the equivalence point of your titration for each experiment based on your graphs.
  14. (Manipulation) Calculate the pH at the equivalence point for each experiment.
  15. (Assumptions and Analysis) Fill in the following table using the observations and data from your experiments.
Assumptions made Testing the assumption If assumptions are wrong ...
The burette is clean and properly recharged between titrations. Repeat each titration at least twice. Different results will be obtained.

Titration A 1

Volume HCl solution in titration flask:___________ Approximate concentration HCl solution: 0.1 M Concentration NaOH from KHP standardization:_________________________
Volume of Base added (mL) pH [H+] (M) [OH-] (M) Indicator Color
0.00
   

Titration A 2

Volume HCl solution in titration flask:___________ Approximate concentration HCl solution: 0.05 M Concentration NaOH from KHP standardization:_________________________  
Volume of Base added (mL) pH [H+] (M) [OH-] (M) Indicator Color
0.00
   

Titration B 1

Volume NaOH solution in titration flask:___________ Approximate concentration HCl solution: 0.1 M Concentration NaOH from KHP standardization:_________________________  
Volume of Acid added (mL) pH [H+] (M) [OH-] (M) Indicator Color
0.00
   

Titration B 2

Volume NaOH solution in titration flask:___________ Approximate concentration HCl solution: 0.05 M Concentration NaOH from KHP standardization:_________________________  
Volume of Acid added (mL) pH [H+] (M) [OH-] (M) Indicator Color
0.00

Discussion

Write a minimum one-page (12 font, single spaced) discussion on the experiment conducted this week. Address at least one question in each category as fully as possible integrating the collected data, providing explanations for the observed trends, and evaluating whether your original assumptions about the experiment were validated by the results. The assignment will be graded on completeness, clarity of the explanations and the meaningful integration of the collected and calculated data. Correct grammar and appropriate format for the chemical formulae and chemical reactions is expected.
  1. (Existing knowledge, research, and views) Provide a definition for the pH and describe how it is calculated.
  2. (Lab skill) Describe the steps required for charging a burette and comment on the importance of each step.
  3. (Lab skill) Describe the steps required for calibrating a pH probe and comment on the importance of each step.
  4. (Lab skill) Describe the steps required for performing a titration and comment on the importance of each step.
  5. (Existing knowledge, research, and views) Classify all your chemicals as acids or bases, strong or weak.
  6. (Analysis) Provide at least two supported arguments for using burettes in titration experiments compared to pipettes, graduated cylinders or syringes.
  7. (Lab skill) Describe the proper way to use and read a burette.
  8. (Analysis) Describe the main difference between the end point and the equivalence point. Describe the method you used identify them in this experiment.
  9. (Analysis) List every species of chemical in the flask after you add the first 2 mL of NaOH solution from the burette into the flask with the HCl solution. Indicate their relative amounts.
  10. (Analysis) List every species of chemical in the flask after you add the first 2 mL of HCl solution from the burette into the flask with the NaOH solution. Indicate their relative amounts.
  11. (Analysis) List every species of chemical in the flask at the equivalence point of the reaction between the HCl solution from the burette into the flask with the NaOH solution. Indicate their relative amounts.
  12. (Analysis) List every species of chemical in the flask after you add 2 mL after the equivalence point of the reaction between the NaOH solution from the burette into the flask with the HCl solution. Indicate their relative amounts.
  13. (Analysis) List every species of chemical in the flask after you add 2 mL after the equivalence point of the reaction between the HCl solution from the burette into the flask with the NaOH solution. Indicate their relative amounts.
  14. (Acquiring competencies) Create a color scale for the universal indicator connecting the observed colors and recorded pH values.
  15. (Analysis) Consider the equivalence point of all your titrations from experiment 2. Provide a supported argument for any changes observed in the equivalence point depending on whether the acid or the base was in the burette.
  16. (Assumptions) You are titrating an unknown acid with a strong base and the pH at the equivalence point is 7. What assumption can you make about your acid? Provide a supported argument for it.
  17. (Interpretation) Compare the titration curves from your experiments where you started with NaOH in the burette. Identify at least one difference and one similarity between them.
  18. (Interpretation) Compare the titration curves from your experiments where you started with HCl in the burette. Identify at least one difference and one similarity between them.
  19. (Interpretation) Compare the titration curves from your experiments where you started with NaOH compared to starting with HCl in the burette. Identify at least one difference and one similarity between them.
  20. (Assumptions) In this experiment each titration was performed once. What assumptions are you making about your collected data?
  21. (Analysis) Predict how many repetitions for each titration would produce valid data. Provide a supported argument for your choice.
  22. (Analysis) Predict the effect an air bubble caught in the burette would have on the outcome of the titration and provide a supported argument for your choice.
  23. (Acquiring competencies) Your burette has an air bubble in it right above the stopcock. Provide a reasonable method for removing it.
  24. (Existing knowledge, research, and views) Describe what the universal indicator is.
  25. (Analysis) If you could only use the pH meter or the universal indicator, which one would choose? Provide at least one supported argument for your choice.