Discovering Buffers

1. Take a small beaker of distilled water and determine its pH. Add one drop of strong acid or of strong base to the water and observe the pH reading on the meter.
2. Now take a small sample of either the standard pH buffer or of any other buffer solution in the lab and add a drop of either strong acid or strong base. Does the reading on the pH meter remain constant or does it change rapidly as it did with the distilled water?

Set-up and calibrate Vernier Go-direct pH meter

1. Connect pH probe to computer via USB
2. Launch Vernier Graphical Analysis on computer
3. In the lower left corner, click on “Mode:XXXX” and change mode to “Event Based”
   1. Choose “Event with Entry”
4. Replace “Event Name” to “NaOH”
5. Enter the units “ml”
6. Optionally click “Average over 10 seconds” and click “Done”
7. In lower right corner click on “pH:####”
8. Click “Calibrate”
9. Choose “Three-point Calibration” from “Perform a” menu
10. Rinse probe with water
11. Place probe in pH 3 solution and wait for reading to be somewhat stable
    1. Enter “3” as the value and press “Keep”
    2. Remove probe and rinse with water
12. Place probe in pH 10 solution and wait for reading to be somewhat stable
    1. Enter “10” as the value and press “Keep”
    2. Remove probe and rinse with water
13. Place probe in pH 7 solution and wait for reading to be somewhat stable
    1. Enter “7” as the value and press “Keep”
    2. Remove probe and rinse with water
14. Click “Apply”

Titration of Acetic Acid

Use the following situation to mimic the set-up below: https://iwant2study.org/lookangejss/chemistry/WASB.html

Perform Titration of Acetic Acid with Sodium Hydroxide

1. Fill Burette with 0.1 M Sodium Hydroxide (NaOH)
2. Measure 50 ml of 0.1 M Acetic Acid into 250ml beaker and add 5 drops of phenopthalein
3. Swirl solution and place cleaned probe into solution
4. Near the upper right corner “View Options” menu (three rectangles), toggle to “Meter”
5. Press “Collect”
6. When reading is stable, press “Keep”
7. In “Keep Point” dialog, enter “0” in the first field since 0ml NaOH has been added to the Acetic Acid
8. Press “Keep Point”
9. Release 3ml of NaOH from the Buret stopcock into the Acetic Acid beaker below
10. Swirl the solution to mix and wait for the meter reading to stabilize
11. Repeat Step 8. remembering to increase the value by 3ml NaOH cumulatively (0,3,6,9…) until the readings are greater than pH 10
12. Repeat the steps an additional 3 additions
13. Click on “Stop”
14. On the “View Options” menu (Upper Right three boxes icon), select “Graph and Table”
15. Click on “Untitled” on the Upper Left Corner
16. Select “Export”
17. Select “.csv”
18. Click on “Export CSV”
19. Navigate to a location to save the table data (as csv) and provide an appropriate filename
20. Share your CSV file from a flash drive to your group and you can now use this data to plot your own graph in Chart Studio to share with your Instructor.
    1. Chart Studio Plot.ly is a free to use system where you can log-in with common single sign-on (Facebook, Gmail, GitHub. Twitter, etc)
    2. Students do NOT require premium features to share charts with instructors

 

Scatterplot Tutorial

Download the data to try in Plot.ly Follow this tutorial on using Plot.ly to generate a graph. However, do not draw a trendline.