Viscosity Experiment

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CHE202, PHYSICOCHEMICAL SYSTEMS 2 , LABORATORY
REPORT 1

EXPERIMENT 1: VISCOSITY
Assistant: Gamze Gümüşlü

Date of the experiment: February 25, 2009
Submission date of the report: March 4, 2009
OBJECT:
The aim of this experiment is to measure the relative viscosity and by obtaining this to determine the viscosity composition curve for a two-component liquid system.

APPARATUS:
1- Electric Weight Scale
2- Pycnometer
3- Pipette
4- Stop Watch
5- Salt Solutions with Varying NaCl concentrations
6- Capillary Viscometer
7- A Short Rubber Tubbing
[pic] [pic]
Salt Solutions with Varying NaCl concentrations Electric Weight Scale [pic] [pic] [pic] Pycnometer Capillary Viscometer Pipette

[pic] [pic]
A Short Rubber Tubbing Stop Watch

PROCEDURE:
1- We determined the weight of each five pycnometer separately by using the electric weight scale and recorded the datas. Then we filled them with salt solutions which have varying NaCl concentrations and while we were doing this we make sure that the solution level in the pycnometer reaches the top of the capillary and it was free of air bubbles. We carefully dried the outside of the pycnometers in order to get rid of the remaning solution drops. We repeated this process five times with five different solutions ( which have different NaCl concentrations 5%, 10%, 15%, 20%, 30% ) 2- The next step was determining the weight of each five pycnometer which were filled with NaCl solutions. Again we recorded this values. 3- We proceeded by placing some amount of water into the capillary viscometer and hold it vertically, meanwhile a short rubber tubing is attached to the small arm of the viscometer and we began squeezing it slowly and carefully as a result the water is drawn over into the feed bulb. Then we stopped squeezing and allow water to run back on its previous rate. While we were doing this we recorded the time which is necessary for the upper meniscus to successively pass the two calibration marks. We did that by the help of the stop watch. 4- Then we continued with the experiment and apply the same process five times for each of the NaCl solutions which have different concentrations, again we recorded all those values.

CALCULATIONS:

1-) To derive equation η1/ η2= (ρ1t1/ ρ2t2) which can be assumed between the absolute viscosities of the two fluids we use equation η =Δpgπr4/(8Vl) where Δp: pressure drop across the tube (g/cm2)

g: gravitational acceleration (cm/sec2)
r: the radius of tube (cm)
V: the volumetric flow rate (ml/sec)
l: the length of tube (cm)
When a liquid is flowing due to gravity only in a tube of length h, we derive equation of Δp= ρgh where the ρ is the density of the solution.
If the physical constants of the viscometer, which are g,h,l,r, and volume, are denoted by A the equation becomes; η=Aρt where t is the outflow time of the liquid
To find the relationship of two liquid we divide two absolute viscosities of them. So the equation becomes; η1/ η2=(ρ1t1)/( ρ2t2)

2-) To find the density of each solution we first determine the weight of the each solution and because of the volume of the pcynometer is constant we can reach the density of the solutions by using equation ρ=m/V where m is the weight of solution and V is the volume of the pcynometer. We determine the weight of solutions by weighting pcynometer empy and full with solution here is the data table TABLE-1

|Number of pcynometers |Salt solutions (%by |Weight of the pycnometer with no |Weight of the pcynometer with |Weight of the solutions | | |weight) |solutions (grams) |solutions (grams)...
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