User:Karlena L. Brown/Notebook/PVOH Research/2012/11/14

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  • Standardize 0.2M NaHCO3 solution with KHP
  • Conduct swelling examinations of each film

Standardization Preparation Protocol

  1. In a clean burette, pour in the 0.2M NaHCO3 solution until it reaches the top
  2. Turn the stopcock at the bottom of the burette to allow the solution to pass through the tip
  3. In a clean beaker, run the solution from the burrette until 0.2M NaHCO3 solution volume reaches the 0.00mL calibration mark
  4. Record the initial starting point and then turn on the stir plate beneath the burette
  5. Next, place a new dry 10mL beaker containing a small stir bar onto the stir plate
  6. While stirring, add ~1g of dry KHP crystals to the beaker
  7. Next, add ~2 drops of bromothymol blue indicator
  8. Begin titrating by turning the stopcock on the burette allowing the 0.2M NaHCO3 solution to steadily stream out
  9. Slow the pace of the 0.2M NaHCO3 solution to drops when the PVOH solution begins to turn red in color
  10. Once the solution completely to turns red, stop titrating by turning the stopcock to OFF position
  11. Record the new 0.2M NaHCO3 volume within the burette


Sample # Original KHP Amount Dried (g) Sample Fraction Cut (g) New KHP Amount Dried (g)
1 6.8079 1/6 1.13465
2 6.8075 1/6 1.13458
3 6.8076 1/6 1.13460

Standardization Calculations

Standardization Trial # KHP Amounts (g) Bromothymol Blue Indicator (drops) Initial Burette Volume(mL) Final Burette Volume(mL) KHP Amount Used (mL)
1 1.13465 2 2.3 10.2 7.9
2 1.12458 2 10.2 19.2 9.0
3 1.13460 2 19.2 29.0 9.8
4 1.13456 2 35.2 46.0 10.8

Swelling Test Protocal

Swelling Test Result Analysis


  • Due to so much 0.2M NaHCO3 solution used for titration, in regards to standardization, the amounts of dried KHP needed to be re-evaluated. Only sixths of the original amounts measured out were be used for standardization.
  • Instead of taking three measurements for standardization, four measurements were taken because one trial of results was thrown out due to inaccurate measurements -- indication / equilibrium point was underestimated (trial #1).