Experiment 12 EDF
Experiment 12 – pH in Blood
Experimental Design Form
EDF 1
Complete only page 1 and your procedural steps on page 2, BEFORE the start of your lab session.
Include a screenshot of your Virtual Lab Feedback form in the Appendix on page 4.
Research Question
How much Restoration liquid will be need to “save the patient” using a blood buffer system?
Hypothesis
25mL of Restoration liquid will be needed.
Glassware and equipment (include quantities)
Glassware / equipment Quantity Glassware / equipment Quantity
Beaker (250mL) 1 Graduated Cylinder 2
Volumetric Flask
(100mL)
1
Pasteur Pipet 1
pH Probe 1
Drop Dispenser 1
Pre-boiled Deionized
Water Bottle
1
Chemicals needed (names and amounts)
Calculations for the preparation of the buffer solution
(Can include as a screenshot in Appendix on page 4, if written by hand)
Procedural Steps, Observations and Changes to the Original Procedure
Chemical (name) Quantity
0.5M H2PO4 36.0mL
1.0M NaOH 12.0mL
0.1M HCl 29.30mL
0.1M NaOH 3.85mL
E x p e r i m e n t 1 2 P a g e | 2
EDF 1 Procedural steps: Use 1 green row for each step. You can add more rows if needed but cannot
exceed this page.
EDF 2 Observations and Changes to original procedure: add these to the row below the procedural step
where the observation or change occurred. Remember to include reasons for changes.
Start by preparing 100mL of a phosphate buffer.
- Transfer 36mL of the 0.5M H2PO4 (phosphate buffer) into a clean 250mL beaker. To this
solution, add 1.0M NaOH while stirring until a pH of 7.45 is reached. Use a pH monitor to
monitor the pH. This buffer solution should now be transferred to a 100mL volumetric flask
and filled until the calibration point with pre-boiled deionized water. Add the formula to the
Microlab program and calibrate the drop dispenser.
- H2PO4 is a clear liquid.
- Put in an automatic stirrer into the beaker to mix the solution.
Titration
- Grab a 250mL beaker and pipet 25.00mL of the buffer solution. The drop dispenser should be
filled with 0.1M HCL and start the Microlab program. Dispense the HCl dropwise into the
buffer solution until the pH drops by 1 unit, then stop the program. This should give a.graph
which should be labelled HCl. Repeat the steps with 0.1M NaOH and title it NaOH. Mark the
graphs to display the acid and base buffer regions.
- HCl is a clear liquid.
- The HCl drops are slow and steady.
- The pH comes down slowly, it comes down by 0.1 by around every 2-3 drops of HCl.
- NaOH is a clear liquid.
- NaOH increases the pH very quickly, a small amount of NaOH was used.
Save the Patient
- Pour 25mL of “Parent Trial” blood into a beaker using a pipet and record the pH. Clean the
drop dispenser and fill with Restoration Solution.
- Add the Restoration Solution to the patient’s blood dropwise and start the Microlab program.
Wait until a pH of 7.45 is restored. Title and print the graph.
- Test Model by “saving the patient” and use the small bottle labeled “patient’s blood.”
- Measure the pH and volume of the sample. Predict how much Restoration Solution was
needed to restore the pH to 7.45. Add the sample to a clean beaker and turn on the magnetic
stirrer and ass the calculated amount of Restoration Solution all at the same time.
- Patient trial blood is a diluted red liquid.
- Restoration that was required to save the patient was 20.3mL of Restoration liquid.
- Add automatic stirrer to make sure the pH reading stays consistent.