User:Moira M. Esson/Notebook/CHEM-581/2012/08/31: Difference between revisions
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== | ==Objectives== | ||
* | # Make PVOH films by acid catalyzed dehydration in H<sub>2</sub>O. | ||
# Make a 500mL stock solution for PVOH(MW 22,000) in H<sub>2</sub>O | |||
# Create four dilute solutions from the prepared PVOH(MW 22,000) stock solution, diluting by 0.75, 0.5, 0.25, and 0.125 | |||
# Measure the viscosity of PVOH (MW 22,000) at the diluted concentrations and the stock solution | |||
==PVOH plus acid films== | |||
#The General Procedure for creating films(described on 08/29/2012) was followed except for the addition of 1-2 drops of acid before heating and stirring the solution | |||
* 0.5 g PVOH (MW 22,000) and 2 drops of 12 M HCl in 3 mL H<sub>2</sub>O | |||
** Actual mass PVOH = 0.5163 g | |||
**'''Note''': After addition of the 12M HCl and heating for ~5 minutes, the gel formed a brown color | |||
* 1 g PVOH (MW 22,000) and 1 drop of 12 M H<sub>2</sub>SO<sub>4</sub> in 6 mL H<sub>2</sub>O | |||
** Actual mass PVOH = 1.0204 g | |||
***'''Note''': After heating the solution for ~5 minutes, the gel formed a brown tint | |||
* 1 g PVOH (MW 22,000) and 1 drop of 12 M H<sub>3</sub>PO<sub>4</sub> in 6 mL H<sub>2</sub>O | |||
** Actual mass PVOH = 1.0040 g | |||
== Preparation of PVOH Stock Solutions== | |||
#In a clean 600mL beaker, place 200mL distilled H<sub>2</sub>O with a magnetic stirrer and heat until ~90°C | |||
#Slowly add 5grams of PVOH (MW 22,000) over a 30 minute period. Continuously stirring. Stir slowly to avoid frothing of the gel. Heat and stir until polymer is completely dissolve | |||
#*'''Note''': The polymer is completely dissolved when the solution is clear(~1hr of heating) | |||
# Let the solution cool to room temperature. | |||
# Pour into a 500 mL volumetric flask and fill with H<sub>2</sub>O. | |||
# Dilute the solution by pouring the following volumes into separate 50 mL volumetric flasks and then filling with H<sub>2</sub>O. | |||
'''Stock Solution Calculations''' | |||
* Stock Solution Preparation for PVOH (MW 22000) | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Initial Mass [g]''' | |||
| align="center" style="background:#f0f0f0;"|'''Additional Mass [g]''' | |||
| align="center" style="background:#f0f0f0;"|'''Total Mass [g]''' | |||
| align="center" style="background:#f0f0f0;"|'''Stock Volume [mL]''' | |||
| align="center" style="background:#f0f0f0;"|'''Concentration ['''M''']''' | |||
| align="center" style="background:#f0f0f0;"|'''Weight percent [%]''' | |||
|- | |||
| 2.0256||4.9902||7.0158||500||6.38E-4||1.40||| | |||
|} | |||
*Serial Dilution of PVOH Stock Solution | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Dilution''' | |||
| align="center" style="background:#f0f0f0;"|''''''M<sub>1'''[mol/L]''' | |||
| align="center" style="background:#f0f0f0;"|''''''V<sub>1''' [mL]''' | |||
| align="center" style="background:#f0f0f0;"|''''''M<sub>2'''[mol/L]''' | |||
| align="center" style="background:#f0f0f0;"|''''''V<sub>2''' [mL]''' | |||
|- | |||
| 1||6.38E-4||6.25||7.98E-5||50|| | |||
|- | |||
| 2||6.38E-4||12.5||1.59E-4||50|| | |||
|- | |||
| 3||6.38E-4||25 ||3.19E-4||50|| | |||
|- | |||
| 4||6.38E-4||35.5||4.78E-4||50|| | |||
|} | |||
==Viscosity of PVOH (MW 22000) Stock Solution== | |||
'''General Procedure''': | |||
#Using an ASTM kinematic viscometer, time the rate at which H<sub>2</sub>O flows from the top most line to the bottom most line. Run at least three trials | |||
#*'''Note''':The actual amount of solution in the viscometer does not matter, but the viscometer can hold no more than 10mL. Approximately 10mL should be used | |||
#Measure the temperature of the surroundings. Record the temperature | |||
#Wash the viscometer with the solution that needs to be tested. Wash by drawing the solution into the viscometer with a pipette pump past the top of the lower bulb and then allowing the solution to drain | |||
#Wash the viscometer at least two times then discard the solution | |||
#Pour approximately 10mL of the solution into the viscometer | |||
#Draw the solution up past the lower bulb of the viscometer using a pipette pump | |||
#Remove the pipette pump and let the solution drain from the viscometer. Once the bottom of the meniscus passes the first mark on the viscometer, start a stopwatch | |||
#Stop the stop watch once the bottom of the meniscus passes the lower mark on the viscometer | |||
#Repeat steps 6 through 8 at least two more times to obtain an average time in seconds for the solution to move between the two marks. | |||
*'''Note''': Solutions should be run through the viscometer with increasing concentration(i.e. The lowest concentrated stock solution should be used first) | |||
'''Viscosity Calculations''' | |||
* Viscosity of pure H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||238.79 | |||
|- | |||
| 2||242.62 | |||
|- | |||
| 3||241.63 | |||
|- | |||
|} | |||
* Average time = 241.01 s | |||
<br> | |||
* Viscosity of 7.98E-5M PVOH in H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||279.37 | |||
|- | |||
| 2||281.97 | |||
|- | |||
| 3||283.12 | |||
|- | |||
|} | |||
* Average time = 281.49 s | |||
<br> | |||
* Viscosity of 1.59E-4 M PVOH in H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||246.42 | |||
|- | |||
| 2||250.31 | |||
|- | |||
| 3||251.86 | |||
|- | |||
|} | |||
* Average time = 249.53 s | |||
<br> | |||
* Viscosity of 3.19E-4 M PVOH in H<sub>2</sub>O at 26°C | |||
{| {{table}} | |||
| align="center" style="background:#f0f0f0;"|'''Trial [ ]''' | |||
| align="center" style="background:#f0f0f0;"|'''Time [s]''' | |||
|- | |||
| 1||273.99 | |||
|- | |||
| 2||276.73 | |||
|- | |||
| 3||278.63 | |||
|- | |||
|} | |||
* Average time = 276.45 s | |||
==Preparation== | |||
*Prepared 500mL stock solution of PVOH (MW 130,000)in H<sub>2</sub>O | |||
==Observations== | |||
*PVOH (MW 130,000) film(prepared 08/29/12) when dried was very rigid and curled slightly | |||
*Preparation of 500mL stock solution of PVOH (MW 130,000)in H<sub>2</sub>O required more time(~2-2.5 hrs). Complete dissolution of the polymer required extra time and more vigorous stirring | |||
**When dissolving the PVOH (MW 130,000) a large gel-like sphere formed in the center of the solution | |||
==Notes== | |||
*An additional 2-3mL H<sub>2</sub>O was added to each solution to aid in the complete dissolution of the PVOH | |||
*Heat was reduced halfway through dissolving the PVOH because the solutions began to boil too rapidly | |||
*When pouring the ~0.5g PVOH (MW 22000) with HCl there was a small loss of sample when pouring the solution into a Teflon dish | |||
*Between the sample run of 7.97E-5 M PVOH solution and the sample run of 1.59E-4M PVOH solution, the viscometer was not washed | |||
Revision as of 20:44, 6 September 2012
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Objectives
PVOH plus acid films
Preparation of PVOH Stock Solutions
Stock Solution Calculations
Viscosity of PVOH (MW 22000) Stock SolutionGeneral Procedure:
Preparation
Observations
Notes
|