Percent error measurement

In carrying out a molar mass determination by freezing point depression, we must choose a solvent in which the solute is readily soluble. Usually, several such solvents are available. Of these, we tend to pick one that has the largest kf. This makes ATf large and thus reduces the percent error in the freezing point measurement From this point of view, cyclohexane or other organic solvents are better choices than water, because their kf values are larger. 

Calculate the percent error between the measured AH and the calculated AH. 

A pharmacist measured 50 mL of syrup USP in a measuring cylinder, and transferred that amount to a beaker. To his surprise, he later observed that 5 mL of syrup USP was still left in the cylinder. What is the percent error in his syrup USP measurement ... 

To use a short-term detector tube for measurement of instantaneous concentration of a contaminant, the pointed ends are broken off and one end of the tube is inserted into a special hand pump supplied with the kit. The pump is then used to pump a specified amount of air through the tube. The technique is relatively simple and effective, although the results may not as precise as with more sophisticated methods. Depending on the contaminants and the conditions of use and the skill, there can be as much as a 25 percent error in some situations. 

Metal Predicted potential Measured potential Percent error... 

It should be noted that estimation errors of 50 percent or 100 percent are not unduly large for airborne asbestos measurements. For example, the estimate of a typical ambient concentration level may be 2 nanograms per cubic meter. The bounds for a 100 percent error would be 1 and 4. Although there is no absolute health... 

However, there is one important use for Eqs. (38) and (39) to estimate the magnitude of the end effects as represented by the second term in Eq. (39). This will let us know how far in from the ends of the vessel the probes must be placed so that end effects can be neglected and the simpler equation used. Bischoff and Levenspiel (B14) present design charts which allow making such an estimation. As an example in a typical packed bed (dt/df — 15) followed by an empty tube these charts show that the measurement points should be placed at least eight particle diameters into the packed section for less than one percent error. For more details see (B14). 

Estimate the diffusion coefficient for 10 compounds through air at 1 atmosphere pressure from the Wilke-Lee adjustment to the Chapman-Enskog theory and compare your results with measurements. What is the percent error of the estimation (assuming that the measurements are correct) What is the primary cause of the differences between the estimated diffusivities ... 

Estimate the diffusion coefficient of 10 compounds in water at 25°C with the Wilke-Chang theory using X = 2.26 and the Hayduk-Laudie theory, and compare with measured values. What is the overall percent error (mean of all absolute percent errors) ... 

The two most common measurements related to accuracy are error and percent error ... 

Percent error Percent error compares error to the size of the thing being measured ... 

Calculate the percent error in the officer s measurement of the Ferrari s speed. 

Which jeweler s official measurement was more accurate Which jeweler s measurements were more precise In each case, what was the error and percent error in the official measurement ... 

This example shows how low-precision measurements can yield highly accurate results through averaging of repeated measurements. In the case of Jeweler A, the error in the official measurement was 0.864 g-0.856 g=0.008 g. The corresponding percent error was (0.008 g/0.856 g)xl00=0.9%. In the case of Jeweler B, the error in the official measurement was 0.856 g-0.856 g=0.000 g. Accordingly, the percent error was 0%. 

The result of Problem 6.25 is inaccurate for a number of reasons, (a) Show that the procedure of averaging the differences of successive Raman shifts is poor in that it throws away all observations but two. (b) Because of the 0.02 cm-1 error in the shifts, it is desirable to use measured shifts for high J values, for which the percent error is smaller. However, centrifugal distortion must then be taken into account. Show that the Raman shifts Ap for J- J + 2 equal... 

The following is a conversion table for absorbance and transmittance, assuming no reflection. Included for each pair is the percent error propagated into a measured concentration (using the Beer-Lambert law), assuming an uncertainty in transmittance of+0.005.1 The value of transmittance that will give the lowest percent error in concentration is 3.368. Where possible, analyses should be designed for the low uncertainty area. 

The accuracy of a measurement can be improved by making replicate measurements and taking the average. All measurements have some inherent uncertainty. But if the uncertainties are random, then half of the measurements should be too big and half too small. The errors will cancel each other out. Accuracy is assessed by calculating the percent error, which is given by the formula ... 

For example, imagine measuring the (arterial) PQ2 of a patient three times and obtaining these values 105, 96.0, and 102 mmHg (in that order). What is the average value Does the data seem precise What is the standard deviation of the measurements What is the percent error ... 

Accuracy is agreement between a measured quantity and the accepted value. Precision is the agreement between replicate measurements. Precision is assessed (but not necessarily improved) by calculating the standard deviation of the measurements. Precision is improved through careful laboratory technique and/or by using more precise measuring devices. Accuracy is improved by replicate measurements and assessed by the percent error of the measurement. 

For a 0.01-pm unit-density sphere, how short must a diffusion experiment be to have as much as 1 percent error in distance measurements How much shorter for a 10 percent error ... 

Quite often when you perform an experiment, your results come close to, but do not actually match, a particular value that you are looking for. You will then want to find out how far off the mark your results were that is, the percent error. For example, suppose you know that the accepted value for the boiling point of vanillin is 83°C, but in your experiment you measured it as 85°C. You could say that you were off by two degrees. Instead, you calculate a percent error by using the formula ... 

Show that the average rate measured over the first 5 min of reaction provides an acceptable approximation to the true initial rate Tq by estimating the percent error associated with this approximation. 

Since even a few percent error in R((o) is crucial to the Kramers-Kronig (K-K) analysis, extra care was taken in all procedures for obtaining absolute values for R(d)). Surface quality is essential for accurate reflectance measurements. Therefore, the surface morphology of each film was checked, both optically and using scanning electron microscopy [269], All the sample surfaces were of excellent optical quality and exhibited specular reflection. Thus, any scattering... 

Introduce a delay time Impedance measurements are taken at the sinusoidal steady state, meaning that the sinusoidal response to the sinusoidal input is unchanging with respect to time. A transient is observed as the system responds to a change from one frequency to another, and this transient is incorporated into the integrated value of the impedance. Pollard and Compte have shown that this transient can introduce as much as a 4 percent error in the impedance response measxued by integration over fixe first cycle. To avoid this undesired error caused by fixe transient, it is better to introduce a delay of one or two cycles between the cheinge of frequency and impedance measurement. 

Workers in a lab in another city have also tested eggs, and they found that a normal eggshell is about 97% CaCOs. Calculate the percent error for your measurement. 

Percent error The density values reported in Table 2-3 are experimental values, which are values measured during an experiment. The density of sucrose is an accepted value, which is a value that is considered true. To evaluate the accuracy of experimental data, you can calculate the difference between an experimental value and an accepted value. The difference is called an error. The errors for the data in Table 2-3 are listed in Table 2-4. 

You are given the errors for a set of density measurements. To calculate percent error, you need to know the accepted value for density, the errors, and the equation for percent error. 

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