Sources of error in viscosity experiment


- This source is good EXPERIMENT 7 Viscosity of gases: Estimation of molecular diameter Expressed most simply, the viscosity of a fluid (liquid or gas) relates to its resistance to flow. The resulting data from these experiments demonstrated that the method is feasible. (5 marks) HET PHYX203 PHYSICS LAN 1202110 VERSION 1. r. Run a series of experiments to establish the ratio of the How do you find the fundamental frequency of an open pipe? In a tube with two open ends f1 = v/2L, λ = v/f = 2L. Task. experiments were analyzed. The patterned bars in the background show the equivalent data for the 24 individual observers of Experiment 1a (there is no equivalent single observer data for this experiment because observers were always sitting together). t1 flow time of liquid 1. η2 is viscosity of water 0. experiment was repeated at least five times at each temperature. Once that is complete you may transition into other individual work. Experiments for the saturated-liquid and saturated-vapor viscosities of R404A, R407C, experimental errors. The viscosity of the fluid sample This type of flow occurs in fluids with low viscosity and high velocity. 6%. In this experiment we will use Stoke’s Law and the concept of terminal velocity to determine the viscosity of glycerin. Two different flow situations will be studied, laminar flow and turbulent flow. Systematic and random errors viscosity regulation in continuous extrusion, the viscosity may be directly measured through on-line measurement or calculated with real-time measurement of viscosity variables [8-12]. Experiments for the saturated-liquid and saturated-vapor viscosities of R404A, R407C, It is always necessary to understand the cause of the error, such as whether it is due to the imprecision of your equipment, your own estimations, or a mistake in your experiment. This was done by measuring the time taken for a range of ball bearings of different sizes to fall through a know distance in glycerine. 0% 14. By measuring the pressure drop and flow rate through a pipe, an estimate of the coefficient of friction (friction factor) will be obtained. Gather four clear glass jars and fill one with water, one with corn syrup, one with cooking oil and one with honey. ie; Simulator Procedure (As performed through Online labs) To measure the kinematic viscosity of a fluid, the uncertainty of the measurement, to compare the measured kinematic viscosity with manufacturer™s value, and to demonstrate the effects of viscosity by comparison of the fall times for spheres of different densities and diameters. In the experiment, tap water was used which contains a lot of impurities that may have reacted with the mud, affecting the mixture. Corn syrup, honey, and corn syrup have much higher viscosities than water or alcohol. (4) One number worth remembering: at room temperature, water has a viscosity of about Using this apparatus, the following experiments can be conducted: 1. Resident Portal Stokes’ Law …. After finding the temperature you can read the viscosity off the graph in Appendix A. Apparatus Figure 1. ie; Simulator Procedure (As performed through Online labs) The purpose of this experiment is to measure the viscosity of unknown oil with a falling ball viscometer. As such, it would be logical to think that water of high viscosity will take longer to swim in than water with lower viscosity. The sample clings to the tip surface, traveling slowly when dispensed. Relevant theory, tasks and introduction sections are available in every virtual experiment. Repeat steps 5 & 6 using the all PVA solutions (PVA-U1, PVA-U2, PVA-C0, PVA-C1, PVA-C2) 12 Procedure Errors can lead to inaccurate results, so understanding the causes of errors can help us minimize the occurrence of errors and improve the quality of the test results. Can be calculate the Relative Viscosity by the relationships: Liquid 1: ethanol (density of ethanol = 0 Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. viscosity regulation in continuous extrusion, the viscosity may be directly measured through on-line measurement or calculated with real-time measurement of viscosity variables [8-12]. The SI unit of viscosity is equal to 10 Poise or 1000 centipoise. 0% 12. Conclusion From the experiment, we are able to understand more about the working mechanism of the different meters used to measure flow. Having established the value of Reynolds' number for flow in the pipe, the value of may be determined using a Moody diagram. ie; Simulator Procedure (As performed through Online labs) Experiment 5 Viscosity and drag Drag force arises when an object moves through a fluid or, equivalently, when fluid flows past an object. In a tube with one open end and one closed end f1 = v/4L, λ = v/f = 4L. Laminar flow occurs in fluids with Some possible sources of errors in the lab includes instrumental or observational errors. Errors due to external influences. 1. 0 6) Write a conclusion summarizing your results. d2 density of water 0. Conclusion The objectives of the experiment to demonstrate Poiseuille’s law and use the relation to calculate In addition to identifying the source of the error, you can describe how it impacts the results, or you might suggest how the experiment might be improved (but only suggest improvement sparingly—not every time you describe a source of error), for example. Impurities in the media can also Abstract: Experiment 1 looks at two fluid properties, density and viscosity. Figure 2 - Experimental results and the theoretical values for the kinematic viscosity of water for five trials. sources involved in viscosity measurements of amine solutions. Introduction. Stokes’ law assumes that the fluid that the sphere is In the SI system, viscosity is expressed in kg m-1 s-1; however, sometimes viscosity values are shown in terms of the equivalent units of N m-2 s or Pa s, where the Pascal (Pa) is the SI unit of pressure and is equal to 1 Newton per square meter (Table A-1). A cause and effect diagram shown in Fig. Image used with permission (CC SA-BY 4. There is a dear prevalence effect. For example, high-viscosity felsic magma will create a tall, steep stratovolcano, because it cannot flow far before it cools, while low-viscosity mafic lava will create a wide, shallow-sloped shield volcano. How Does the Consistency of a Liquid Impact Magnetic Attraction – This experiment shows how the viscosity of a liquid impacts how fast (or slow) the objects move toward a magnet. Now, repeat the experiment by changing the diameter of the ball. 2746. Calculate the viscosity of the fluid using the following equation, where g is acceleration due to gravity (981 [cm/s 2]). Errors in parallel disk rheometry can arise from many sources, such as uncertainties in the gap size [1], lack of parallelism in the plates [2], viscous heating effects [3], and wall-slip errors [4]. 0; Synapticrelay). Errors such as moistening of the inside surfaces of the gauge, splashing of rainwater from the collector and pouring of water into the already filled bucket during an intense rain can only be corrected by some correction factor. The data collected from the falling ball experiment did not verify Stokes’ Law, though it did show that the revised version of Stokes’ Law correcting for Reynolds Number was fairly accurate. Carefully drop one marble into each jar. Other less viscous and more volatile samples, such as ethanol Calculate the viscosity by the relationships: η1 η2 = t1d1 t2d2 η1 is viscosity of liquid 1. 19, Table 2. 0% 2. Calculate the viscosity by the relationships: η1 η2 = t1d1 t2d2 η1 is viscosity of liquid 1. These ways included using a measuring beaker, Eureka can, and density bottle; these different ways are gone into more detail in the methods section. d1 density of liquid 1. Density was measured three separate ways, each having its own level of accuracy. One of the experiments did not provide sufficient data for analysis. ment is to “inflate sample point estimates to known population totals to compensate for survey nonresponse and other aspects of the sample design” (Bureau of Justice Statistics, 2008b, p. In laminar flows, fluid particles move in layers, sliding over each other, causing a small energy exchange to occur between layers. 3 summarizes most of the uncertainty sources engaged in the experiment. Experiment #7: Osborne Reynolds’ Demonstration. This can be written F = A dv dx (1) where F is the internal friction of viscosity between layers of area A and is known as the coe cient of viscosity of the liquid and has units N:s=m2. 11. Example : The 17th century Danish astronomer, Ole Rømer, observed that the periods of the satellites of Jupiter would appear to fluctuate depending on the distance Random and systematic errors are types of measurement error, a difference between the observed and true values of something. 250 Welsey Oaks Drive. As the additives are selected, using either a weight or molar concentration, the refractive index and viscosity values of the new solvent are automatically updated to account for Experiment 1 Viscosity Measurement Purpose The purpose of this experiment is to measure the viscosity of a glycerin-water mixture with a Thomas-Stormer viscometer. The final experiment had possible errors due to the experimental setup. voltages may be generated in p. In this paper, a hypothetical case is discussed to demonstrate that the analysis of data can detect the Experiment 6: Viscosity (Stoke’s Law) Viscosity is a property of uids (liquids and gases) which determines how much resistance is experienced by an object trying to move through the uid. t2 flow time of water. Gases have much smaller viscosities than liquids. This class of errors usually causes about half of the measurements to be too high and the other half of the measurements to be (3)Viscosity is an intrinsic property of the fluid, although it can depend on temperature (in some cases, quite strongly). 0% 6. Experiment Design fluctuate between trials as it did in the data. η is the viscosity of the air, which depends on temperature. The common practice is to calibrate viscometers by a step-up technique, using a series of instruments and test fluids, based on the viscosity of water. PIL is the pressure gradient; R is the radius of the rods; M is the mass of fluid flowing in time, T; and /J is the kinematic viscosity, the viscosity divided by the density. This experiment measured the CV for each hemacytometer model with multiple dilution steps. Small D. 997 g/cm3. DC Errors. Cause and effect diagram for uncertainties in viscosity measurements of a MEA / water mixture . Do not list all possible sources of errors there. 0% 10. In this take home lab you will need to calculate the ratio of the viscosity of 2 common household fluids such as oil, honey, syrup, or molasses. Memphis, TN 38109. Environmental errors can also occur inside the lab. Equation 1 is known as Newton’s Law of Viscous Flow[2]. Identify 2 fluids that you will be using to measure viscosity. ! Random Errors! Random Errors These changes may occur in the measuring instruments or in the environmental conditions. In nature and in laboratory experiments, flow may occur under two very different regimes: laminar and turbulent. Errors caused by personal technique:-not thoroughly mixing blood-inadequate mixing of diluted specimen-failure to discard first few drops-counting cells inaccurately (skipping cells, counting cells twice, counting on wrong borders)-not loading chamber properly (overfilling, trapped air bubbles)-calculation error-clerical error Random and systematic errors are types of measurement error, a difference between the observed and true values of something. As the additives are selected, using either a weight or molar concentration, the refractive index and viscosity values of the new solvent are automatically updated to account for Results of this experiment show that the falling ball and rotational viscometer methods of measure the viscosity of glycerin were inaccurate. (Note that the OR's in the table are age-adjusted, through a mathematical modeling procedure called multiple logistic regression, so our crude OR's will differ in some cases. Here are the top 5 pipetting errors to watch out for in your next project: 1. Rinse 2x with sample PVA, determine viscosity of stock PVA 3x 7. This means: if a fluid with a The purpose of this experiment was to use stooke's law to estimate the viscosity of glycerine. In (10) T is the Cel-sius temperature. This experiment was first performed by Osborne Reynolds 5. This led me to the research question: “How does the salinity of brine affect its viscosity (Pas 2. Can be calculate the Relative Viscosity by the relationships: Liquid 1: ethanol (density of ethanol = 0 In this experiment you will investigate the frictional forces inherent in laminar and turbulent pipe flow. 3. All real fluids (except Common errors include; inaccurately measuring refracted and incident angles, incorrectly drawing refracted and incident rays, and incorrectly drawing the block. A weight, W, is used to drive a rotor that is partially submerged in a sample of liquid. Calculate the value of r 2 / v in each time. In both cases, adsorption of the RANDOM ERRORS Random errors are usually due to unknown variations in the experimental conditions. If you are in need of assistance with any of the questions, please come see Types of Errors! Systematic Errors! – uncertainties in the bias of the data, such as an unknown constant offset, instrument mis-calibration! – implies that all measurements are shifted the same (but unknown) amount from the truth! – measurements with a low level of systematic error, or bias, have a high accuracy. C. Run a series of experiments to establish the ratio of the Students were assessed based on their data collection, analysis, and conclusion in their lab report. 0% 16. 5). For example, if you were doing an investigation into the effect of leaf area on the rate of transpiration, and the temperature in the laboratory increased while you were doing your experiment, then you can't be sure that all the differences in rate of transpiration were entirely due to differences in leaf area. values of d, V, vf, and vr you will determine through measurement 3 Millikan Oil-Drop Experiment Viscosity Review Today will be a silent, individual work period. We also know the advantages and disadvantages of the venturimeter, orifice plate meter and rotameter. However, as we conduct the falling sphere experiment we do not directly measure terminal velocity; we measure the distance the bead travels, d, over a certain amount of time, t. 0% 8. You must use (10) as the first step in evaluating the viscosity. Note that this First of all, when we talk about “sources of error” we are not talking about mistakes that were made in your project. One of the major research aspects of laboratory science is physical and chemical testing, and its test findings are the primary scientific basis for assessing product quality. Thus our vector of measurements, x, should be: This is because the viscosity of a liquid can also be observed by how slow (or fast) it takes to pour the liquid. If we conduct the step strain experiments at different intervals, we’ll find that for each time we’ll get a different relaxation – the overall relaxation is the sum! G(t) = ΣGk * exp(-τττ/l k) The type of viscosity yielded by your viscometer’s measurements depends on the kind of viscometer you’re using, but it’s usually either dynamic or kinematic. I hope you enjoyed the experiment. In volumetry, calibration of the dead space is required; in gravimetry, the influence of buoyancy has to be taken into account. 25%. Two of the experiments provided results consistent with the known value for the viscosity. The Reynolds Number Demonstration is a classic experiment, based on visualizing flow behavior by slowly and steadily injecting dye into a pipe. Some possible sources of errors in the lab includes instrumental or observational errors. In 1961, Sanders and Skerry concluded that the position of the coverslip could introduce a difference of 7. Where - is the molecular viscosity (1. Rinse viscometer 2x with water, determine viscosity of water 3x 6. Discussion of Errors The terminal velocity is likely tobe the major source of uncertainty since we are ignoring the uncertainty in the densities. However, the two main failures in rotational rheometers are considered to be edge failure [6] and radial migration, 5, In this take home lab you will need to calculate the ratio of the viscosity of 2 common household fluids such as oil, honey, syrup, or molasses. How would, for example, a more viscous liquid like corn syrup or cornstarch and water cool? Also, I would like to test some semi-solid things (like jello or play-doh!) to see how that changed it. 891 poise. Both of these errors in the experiment do not have simple fixes, as they were committed by me, the experiment designer and conductor. All fluids, from liquids to gases illustrate the property of viscosity to some degree. The experimental procedure is very involved, and therefore a variety of precautions needs to be observed to eliminate errors. The solid bars show miss and false alarm errors for Experiment 1b. Use a photoelectric sensor for timing experiment. Viscosity is the measure of a fluid’s resistance to flow, or in scientific terms, of the internal friction given it by its molecular makeup. In kitchen refrigerator terms, honey and mustard have . In sorption measurements, volumetric or gravimetric procedures are commonly used to determine the amount adsorbed. Users of laboratory standard platinum resistance thermometers need take more care to eliminate self heating errors. Take, for example, a sample that contains large, sticky molecules – like glucose. Such errors may come from draughts on the balance pan, for example (though this seems pretty close to a blunder), or maybe from impurity in the chemicals used. Students were required to identify two possible sources of error, identify two ways to improve their experiment, explain how the different viscosities affected the results, and confirm or disprove their hypothesis. the data in the table. In general, the drag force grows larger with increased flow velocity, but viscosity is a complex phenomenon that cannot be reduced to the simple relationship “drag force is proportional to velocity”. The viscosity of a gas is determined in particular by the rate of transfer of the flow momentum from faster moving layers (laminas) to slower ones. Your goal is to identify only those significant for that experiment! For example, if the lab table is not perfectly leveled, then for the collision experiments (M6 – Impulse and Momentum) when the track is supposed to be horizontal, results will have a large, significant The Ostwald method is a simple method for the measurement of viscosity, in which viscosity of liquid is measured by comparing the viscosity of an unknown liquid with that of liquid whose viscosity is known. 46% and 4. Experiment 5 Viscosity and drag Drag force arises when an object moves through a fluid or, equivalently, when fluid flows past an object. 0% 4. Example : The 17th century Danish astronomer, Ole Rømer, observed that the periods of the satellites of Jupiter would appear to fluctuate depending on the distance In a study using five observers, errors due to pipettes and hemacytometers were 9. Let us assume that, in a separate set of experiments we determined ρ s and ρ f and the associated errors. The instruction manual contains experimental What are the possible sources for errors in a lab experiment of Effects of Temperature on Yeast Catalase and Hydrogen Peroxide? Other than human error, what other errors could happen during lab? The units of the viscosity as given in (5) are gm cm-1 s-1 also called a Poise. , kg·m −1·s ). experiment, using a list of common buffer and formulation additives. The dimensionless Reynolds number is used to classify the state of flow. To see how successful my experiment was, I will be comparing my results with those from external sources such as a Textbook; this would therefore determine how accurate my experimental results were. ) The amount of cooling is unlikely to be a source of major error, but it is there nevertheless. (901) 612. Measure the viscosity coefficient of a liquid using falling sphere method. Examples of causes of random errors are: electronic noise in the circuit of an electrical instrument, irregular changes in the heat loss rate from a solar collector due to changes in the wind. The deviation of the individual measurements from the average viscosity value at each temperature did not exceed ±0. Plot a graph with r 2 along X axis and terminal velocity along Y axis. 26%, respectively. 12/21/2018 WuBo laboratory glassware Lab Glassware information experiments, which are designed to introduce the students to density and viscosity determinations using two viscometer types, Ostwald and Falling-Sphere Viscometer. PRINCIPLE The principle of the viscometer is to determine the falling time of a sphere with known density and diameter within a fluid filled inside glass tube. internal friction of viscosity which is a force proportional to the velocity gradient. This means: if a fluid with a To see how successful my experiment was, I will be comparing my results with those from external sources such as a Textbook; this would therefore determine how accurate my experimental results were. If I were to change one thing about the experiment, I would test more liquids. 2. 15 x 10 3 Ns/m2 at 15°C) and 3 is the density (999 kg/m at 15°C). Explain how you will attempt to eliminate or reduce the effect of these errors on the experimental data, if you are given an opportunity to repeat this experiment. Not Accounting for the Viscosity of a Sample. The sources of these random errors cannot always be identified and can never be totally eliminated in any measurement. The SI physical unit of viscosity is the pascal-second (Pa·s), (i. fluctuate between trials as it did in the data. The answer should be in units of kg/cm s, or mPa-s. The constant out in front is obviously the viscosity at T = 20 C. We can calculate the coefficient of viscosity of the liquid by using the slope of the graph. The derived mathematical expression was used to identify ¸ Analysis of Errors in Viscosity Measurement January 2015 Page 4 of 7 0. The viscosity of the polymer melt at the screw tip of the extruder varies due to disturbances during the extrusion process. Equipment Set Up: Additional equipment required: Stop watch, Internal Vernier calliper. Here, usually the viscosity of given liquid is measured with respect to water whose viscosity is known very accurately at different temperatures. 64872 X 10-3; f). Sample data Values quoted are the mean of at least three readings. After a step-strain experiment, the stress of viscoelastic materials decreases exponentially: G(t) = G 0 * exp (-ττττ/l) 3. He finally published the law in 1827 and generalized his observations in single statement: The current flowing through the resistor is directly proportional to the voltage applied across it. t. (3)Viscosity is an intrinsic property of the fluid, although it can depend on temperature (in some cases, quite strongly). You will start by working on a series of questions to review viscosity. with a high viscosity will have a high resistance to flow and will require a lot of force to be able to move through it. (4) One number worth remembering: at room temperature, water has a viscosity of about errors) and random errors • Uncertainty analysis addresses fidelity and is used in different phases of an experiment, from initial planning to final reporting – Attention is needed to ensure uncertainties do not invalidate your efforts • In propagating uncorrelated errors from individual measurement to culate the kinematic viscosity of our test fluid: (1) r is the (dimensionless) geometrical constant, 3. ’s due to thermoelectric effects caused by the joining of dissimilar metals in the construction of the p. In this method viscosity of liquid is measured by comparing the flow times of two liquids of equal volumes using same viscometer. Objective Viscosity is basically friction inside a liquid - it is how much resistance a fluid gives to any force applied to it. Students were assessed based on their data collection, analysis, and conclusion in their lab report. For accuracy, have students repeat the experiment and calculate an average viscosity. Results of this experiment show that the falling ball and rotational viscometer methods of measure the viscosity of glycerin were inaccurate. 1 is a schematic of the viscometer. It is always necessary to understand the cause of the error, such as whether it is due to the imprecision of your equipment, your own estimations, or a mistake in your experiment. At low pressures, thermomolecular flow and pressure differences according to Knudsen's law disturb measurements. The virtual experiments are: Ohm performed repeated experiments on a resistor, applied different voltages, measured current and found relationship between these quantities. The greater the viscosity, the slower an object will move through the liquid. Experiment Design To measure the kinematic viscosity of a fluid, the uncertainty of the measurement, to compare the measured kinematic viscosity with manufacturer™s value, and to demonstrate the effects of viscosity by comparison of the fall times for spheres of different densities and diameters. Conclusion The objectives of the experiment to demonstrate Poiseuille’s law and use the relation to calculate SOURCE: NORC at the University of Chicago (2009, p. The water temperature may also affect mud homogeneity because a higher water temperature will mix the bentonite better. You can imagine this with hot glue or melted chocolate. For comparison, the viscosity of water is approximately 1 mPa-s. The intrinsic viscosity of polymer solutions is widely used for characterizing the molecular sizes of polymers. Kinematic viscosity has a strong dependence on temperature. Instrumental errors can occur when the tools are not functioning exactly as they should be. The fluid on the left has a lower viscosity than the fluid on the right. 0% 0° 5° 10° 15° 20° 25° 30° Percent The vi scosity (shear viscosity) of a Newtonian liquid is normally measured by a relati ve technique in an instrument calibrated using a liquid of known viscosity. Worse yet, there is another a hiding in . Ideally you would use fluids that you also used in the viscosity lab. You can compare the percentage differences between your values for viscosity for different diameters and the calculated uncertainty from your measurements. Viscosity demonstration. The sources of these errors may come from the water used. e. Fig. Use a stopwatch to time a falling sphere, and compare results with the photoelectric timing method. If you made a mistake the best thing to do would be to go back and fix it. errors) and random errors • Uncertainty analysis addresses fidelity and is used in different phases of an experiment, from initial planning to final reporting – Attention is needed to ensure uncertainties do not invalidate your efforts • In propagating uncorrelated errors from individual measurement to The sources of these errors may come from the water used. 12).