OBJECTIVES
- Standardize 0.2M NaHCO3 solution with KHP
- Conduct swelling examinations of each film
Standardization Preparation Protocol
- In a clean burette, pour in the 0.2M NaHCO3 solution until it reaches the top
- Turn the stopcock at the bottom of the burette to allow the solution to pass through the tip
- In a clean beaker, run the solution from the burrette until 0.2M NaHCO3 solution volume reaches the 0.00mL calibration mark
- Record the initial starting point and then turn on the stir plate beneath the burette
- Next, place a new dry 10mL beaker containing a small stir bar onto the stir plate
- While stirring, add ~1g of dry KHP crystals to the beaker
- Next, add ~2 drops of bromothymol blue indicator
- Begin titrating by turning the stopcock on the burette allowing the 0.2M NaHCO3 solution to steadily stream out
- Slow the pace of the 0.2M NaHCO3 solution to drops when the PVOH solution begins to turn red in color
- Once the solution completely to turns red, stop titrating by turning the stopcock to OFF position
- Record the new 0.2M NaHCO3 volume within the burette
REPEAT THE ABOVE STEPS AGAIN FOR THE NEXT TWO KHP SAMPLES
| Sample #
|
Original KHP Amount Dried (g)
|
Sample Fraction Cut (g)
|
New KHP Amount Dried (g)
|
| 1 |
6.8079 |
1/3 |
1.13465
|
| 2 |
6.8075 |
1/3 |
1.13458
|
| 3 |
6.8076 |
1/3 |
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
Notes
- 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 thirds 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).
|
PVOH Research
