Determination of the viscosities of aqueous polyethylene glycol solutions in water by Ostwald viscometer Full name: Tran Thi Thu Tra Student ID: 20191129 Instructor: Date of submission: 05/09/2022 I Introduction One of the most significant factors to describe a fluid is its viscosity, which is a measurement of how much resistance is encountered when moving an object through it In fluid dynamics, viscosity is an important parameter [1] This experiment's research method is to examine the flow of the solution via the capillary naturally The viscosities of aqueous polyethylene glycol solutions in water depend on the concentration of aqueous polyethylene glycol solutions in water.[2] This experiment showed the progressive relationship between the viscosities of aqueous polyethylene glycol solutions in water with the C% mass of polyethylene glycol Due to this progressive relationship, the purpose of the experiment was determined The experiment aimed to determine the viscosities of aqueous polyethylene glycol solutions in water by Ostwald viscometer This experiment hypothesizes that in the small concentration range of aqueous polyethylene glycol, the concentration of aqueous polyethylene glycol solutions increased, and the viscosities of aqueous polyethylene glycol solutions would be increased.[2] II Methodology The viscosities were measured by Ostwald viscometer (China, 220mm) Ostwald viscometer was cleaned and rinsed by a wash bottle Ostwald viscosity was rinsed with pure water three times before carrying out Ostwald viscometer was put in the thermostat which was 22oC Pure water was transferred 10ml into tube of the viscometer by the pipette (China, 20ml;0.1ml) The rubber bulb (Bio BasicCanada, 60 ml) was put into tube of the viscometer to blow slowly pure water over the line a was approximately 1cm Pure water was still at the bulb of tube of the viscometer Each experiment was waited about five minutes to be stable the temperature of pure water after conducting to measure The experiment will be carried out Pure water flowed naturally The stopwatch counted the time when the liquid flowed from line a to line b tube of the viscometer The time was determined The experiment was run three times, and the average result was used The viscosity of polyethylene glycol solutions was measured similarly Ostwald viscometer was cleaned and rinsed with polyethylene glycol solutions three times The experiment was conducted with c= 5;8;10;15;20;25% mass of polyethylene glycol in water The experiment was conducted from low concentration to high concentration of polyethylene glycol solutions Ostwald viscometer was put in the thermostat which was 22oC Each experiment waited about five minutes to be stable the temperature of polyethylene glycol solutions The time of polyethylene glycols was counted by the stopwatch After each experiment, the Ostwald viscometer was rinsed by the next polyethylene glycol solutions to measure When a liquid was put into the capillary, its viscosity was directly proportional to the flow time t and density ρ, and the viscosity of a liquid was calculated: η=k.ρ.t (1) with k: viscometer constant The time of distilled water flowed to determine the viscometer constant at the same temperature and liquid volume ηo=k.ρo.to (2) with ηo: viscosity of the distilled water to the time of distilled water flowed from the line a to the line b η/ηo=ρ.t/ρo.to η=ηo ρ.t/ρo.to A liquid had a low concentration, with ρ=рo: η=ηo t/to The characteristic viscosity was determined: η=(η-ηo)/ ηo =η/ηo-1=t/to-1 III Result Figure shows the progressive relationship between the viscosities of aqueous polyethylene glycol solutions in water with the C% mass of polyethylene glycol The dependency diagram shortened viscosity on C% quality is an inverted straight line and fits a quadratic trendline: y= 0.1459x + 2.726 with an R2 of 0.9926 The characteristic viscosity of polyethylene glycol in water is 2.73 m N.s/m2 Figure The shortened viscosity of aqueous polyethylene glycol solutions in water IV Discussion The relationship between the viscosities and mass of aqueous polyethylene glycol in water was progressive at the same time The relationship between the viscosities of aqueous polyethylene glycol solutions in water and the C% mass of polyethylene glycol was calculated and determined The characteristic viscosity of aqueous polyethylene glycol solutions in water is 2.73 m N.s/m2 In the small concentration range of aqueous polyethylene glycol, the concentration and the viscosities of aqueous polyethylene glycol solutions increased at the same time When the concentration of aqueous polyethylene glycol solutions increased with c= 5;8;10;15;20;25% mass of polyethylene glycol in water, the viscosities of aqueous polyethylene glycol increased These findings demonstrate that the number of aqueous polyethylene glycol viscosities has significantly increased:5% mass of polyethylene glycol, the viscosity is 1.131 m N.s/m2; c= 25% mass of polyethylene glycol, the viscosity is 2.470 m N.s/m The viscosities of aqueous polyethylene glycol solutions increased two times after increasing the concentration of aqueous polyethylene glycol solutions Despite the fact that there is still space for error in our results owing to a variety of factors: instrumental error, temperature error, and calculation error So, the measurement result has errors V Conclusion The relationship between the viscosities and mass of aqueous polyethylene glycol in water was progressive at the same time The characteristic viscosity of aqueous polyethylene glycol solutions in water is 2.73 m N.s/m2 In the small concentration range of aqueous polyethylene glycol, the concentration and the viscosities of aqueous polyethylene glycol solutions increased This experiment had some errors: instrument error, temperature error, and calculation error The instrument should be replaced with one from the stockroom to fix the issue REFERENCES [1] Kopeliovich, Dmitri, “Effect of Oil Viscosity on Hydrodynamic Friction of Engine Bearings.” SubsTech Substance and Technologies, Feb 2018 [2] Cao Hong Ha et al., Thi Nghiem Hoa ly [Physical chemistry laboratory manual], (in Vietnamese) Nha xuat ban Bach Khoa Ha Noi, 2020 APPENDIX Raw and Processed Experimental Data Table Raw and processed of the viscosities of aqueous polyethylene glycol in water Mass of polythylene glycol in water(C%) t(s) 34.59 1.131 0.177 3.54 38.47 1.258 0.309 3.86 10 41.30 1.351 0.406 4.06 15 50.88 1.664 0.732 4.88 20 63.66 2.082 1.166 5.84 25 75.52 2.470 1.570 6.28 ᵑ ᵑr ᵑr/C (m N.s/m2) ... between the viscosities of aqueous polyethylene glycol solutions in water and the C% mass of polyethylene glycol was calculated and determined The characteristic viscosity of aqueous polyethylene glycol. .. viscosity of aqueous polyethylene glycol solutions in water IV Discussion The relationship between the viscosities and mass of aqueous polyethylene glycol in water was progressive at the same time The. .. glycol solutions in water is 2.73 m N.s/m2 In the small concentration range of aqueous polyethylene glycol, the concentration and the viscosities of aqueous polyethylene glycol solutions increased