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Titration of a Strong Acid

Procedure 1 (click to view assignments for this procedure)

PLEASE NOTE: Titration requires several steps in order to obtain exact results.

1. Take a clean Erlenmeyer flask from the Glassware shelf and place it on the workbench.

2. Add 25 mL HCl (of unknown concentration) to the flask.

3. Add 2 drops of phenolphthalein to the flask.

4.Take a burrete from the Glassware shelf and place it on the workbench.

5. Fill the burette with 50 mL of 1M NaOH solution. Record this initial volume.

6. Drag the flask to the lower half of the burette so that the two will be connected.

7. Open the Data window and click on the flask. Click the Pushpin icon in the blue bar of the Data window to lock its display to the contents of the flask.

8. Take a pH meter from the Tools shelf and drop it on the flask. Record the initial pH of the solution.

9. Open the Properties window and click on the burette. Enter "1" in the amount to add, and click the flow button to drip 1 mL of NaOH into the flask. Record the pH of the solution in the flask.

10. Continue to add NaOH in 1 mL increments. Record the pH for each milliliter added.

11. The pink color will appear in flask all at once when the endpoint is either reached or crossed. Record the burette volume and pH at which this occurs.

12. Continue to add 5 more increments of 1 mL and record the pH at each point.

13. Detach the flask from the burette and drag it to the recycling chute.

14. Take a new flask from the Glassware shelf and place it on the workbench.

15. Add 25 mL of HCl and 2 drops of phenolphthalein to the flask.

16. Refill the burette to 50 mL NaOH.

17. Based on the results of the previous titration, add enough NaOH solution - all at once - to get to 1 mL BEFORE the endpoint.

18. Enter 1 as the amount to add and add NaOH DROP-WISE into the flask. Record the pH and volume until the endpoint is reached and several drops after it is reached.

Assignment 1 of Procedure 1
Show All Calculations.

1. Create a graph of pH vs. volume of added NaOH from the first trial. Add in the data near the endpoint from the second trial.

2. Find the equivalence point from the graph.

3. At what point (volume) did your solution turn pink?

4. What is the pH at the equivalence point?

5. What is the equivalence point volume of NaOH?

6. Calculate the molarity of the HCl unknown from the volumes of acid and base at the equivalence point and the molarity of the NaOH.

(Enter Assignment Report)

Assignment 2 of Procedure 1

Conclusion

Summarize the experiment in one or two paragraphs. Restate the overall purpose of the experiment. What were your results (from each procedure)? What are possible sources of error? What did you enjoy learning about this experiment?
(Enter Assignment Report)

Info that I have:
Initial volume 50.00mL of NaOH solution
0.22 pH meter of the solution in the flask:
With one drop of NaOH into the flask the pH went to 0.27
These are my results after that first drop until the solution turned pink (one drop at a time).
1-0.32
1-0.37
1-0.42
1-0.48
1-0.54
1-0.60
1-0.67
1-0.75
1-0.84
1-0.95
1-1.09
1-1.28
1-1.59
1-7.00
ending point

1-PH:12.39 volume: 40.92mL

5 more after that
1-12.68
1-12.84
1-12.96
1-13.05
1-13.12
1-13.17

Solution Preview

Titration of Unknown HCl solution with 1 M NaOH

1. Create a graph of pH vs. volume of added NaOH from the first trial. Add in the data near the endpoint from the second trial.

Response: Please see the attached Excel file to see the titration curve. All you do there is plot the pH against total volume of NaOH. As you did not have data for the second trial, I could not add that to the graph. You can do that yourself.

2. Find the equivalence point from the graph.

Response: The equivalence point is the point at which equal quantities of opposite solutions exist to cancel each other out. For example 0.05 mol HCl and 0.05 mol NaOH. ...

Solution Summary

This solution provides answers to various questions regarding the titration of a strong acid.

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