Less Than 5 Percent Error
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What Is A Good Percent Error In Chemistry
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What Does Percent Error Tell You
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What Does Percent Error Mean In Chemistry
the App or go to Socratic.org/ios on your iPhone Enter your phone number and we'll send you a download link Text me or go to Socratic.org/ios on your iPhone What percent error is too high? Chemistry Measurement Accuracy, Precision, and Percent Error 1 Answer Write your answer here... Start with a one sentence answer Then teach the error analysis physics lab report underlying concepts Don't copy without citing sources How to add symbols & How to write great answers preview ? Answer Write a one sentence answer... Answer: Explanation Explain in detail... Explanation: I want someone to double check my answer Describe your changes (optional) 200 Cancel Update answer 12 Ernest Z. Share Mar 25, 2016 Answer: The acceptability of a percent error depends on the application. Explanation: In some cases, the measurement may be so difficult that a 10 % error or even higher may be acceptable. In other cases, a 1 % error may be too high. Most high school and introductory university instructors will accept a 5 % error. But this is only a guideline. At higher levels of study, the instructors usually demand higher accuracy. Was this helpful? Let the contributor know! Yes Post comment 1500 Add an answer Write your answer here... Start with a one sentence answer Then teach the underlying concepts Don't copy without citing sources How to add symbols & How to write g
Science Psychology Humanities English Grammar U.S. History World History ... and beyond What's Next Socratic Meta Scratchpad Ask question Log in Sign up Chemistry Science Anatomy & Physiology Astronomy Astrophysics beta Biology Chemistry Earth Science Environmental Science Organic Chemistry Physics what percent error is considered accurate Math Algebra Calculus Geometry Prealgebra Precalculus Statistics Trigonometry Social Science Psychology Humanities English what does a low percent error mean Grammar U.S. History World History ... and beyond What's Next Socratic Meta Scratchpad Questions Topics × Accuracy, Precision, and Percent does percent error measure accuracy or precision explain Error Chemistry Measurement Accuracy, Precision, and Percent Error Add yours Lab Experiment #1: Introduction to Scientific Investigation. by Dr. Hayek Thank 11 Flag lesson Tip: This isn't the place to ask a question https://socratic.org/questions/what-percent-error-is-too-high because the teacher can't reply. Post More videos Key Questions What does accuracy in chemistry mean? If a measurement is accurate, that means that it's close to the actual value of the thing being measured. For example, if my cat weighs 6500 grams and a scale said it weighed 6400 grams, this measurement would have moderately good accuracy. OK. misterguch · 1 · 1 comment · Jul https://socratic.org/chemistry/measurement-in-chemistry/accuracy-precision-and-percent-error 3 2014 How can precision be measured? To measure precision, just measure something a whole bunch of times with some measuring tool. If you get the same answer every time, you've got a precise measurement. Typically, precision manifests itself in the number of significant figures present in a measurement. If a balance can read the mass of something to 1.488 grams, we assume that it's precise to the nearest 0.001 gram. This may or may not actually be the case. misterguch · 1 · 4 comments · Mar 24 2014 Why is percent error important? Percent error tells you how badly things went wrong. Here's the deal: Whenever you do an experiment, things go wrong - that's true for anybody no matter how good they are. Things get spilled, things are impure, equipment is imprecise... you get the idea. No matter who you are or how long you've been doing science, this will always be the case. A percent error calculation simply tells you the magnitude of the mistakes that took place during the experiment. If you have a 5% error, then you've done pretty well. A 95% error suggests that you might want to try som
key point is that Ka and Kb values are typically known only to an accuracy of ±5%. So it is reasonable to make approximations if http://www.chemteam.info/AcidBase/five-percent-rule.html they remain within the ±5% range of the true answer. (And remember, the true answer is not within our grasp. Another way to view the 5% is that the Ka and Kb values have a built-in error and http://www.owlnet.rice.edu/~labgroup/pdf/Error_analysis.htm that the true answer remains hidden within that ±5% error.) So, the 5% Rule follows. I'll state it for acids and comment on the parallel expression for bases further down. If the expression (x / [HA]o) times percent error 100 is less than or equal to 5%, we consider the approximation valid. Now, for those of you that are totally confused, my recommendation is to back and study the Ka and Kb links provided above. Here's a brief description of the above expression: 'x' is the value being calculated in the linked Ka tutorial. It is the [H+], the value that will give us our pH [HA]o is the original starting concentration of does percent error whatever weak acid was used in the problem. This value is generally provided in the problem. The approximation stems from the term '[HA]o minus x.' The 'minus x' portion is dropped as part of the problem solution, thus resulting in an approximation. By the way, what is being calculated just above is called the 'percent dissociation.' For bases, the x represents [OH¯] and the orginal starting concentration would be represented [B]o. In the Kb calculations, the term '[B]o minus x' would have the 'minus x' dropped. The 5% Rule for bases is: If the expression (x / [B]o) times 100 is less than or equal to 5%, we consider the approximation valid. In calculating the pH of a weak acid or a weak base, use the approximation method first (the one where you drop the 'minus x'). Then apply the 5% rule. If you exceed 5%, then you would need to carry out a calculation that does not drop the 'minus x.' This would result in quadratic equation, which would be solvable. It would just be tedious. Here is an example of a problem where 5% is exceeded: The Ka of HF is 6.46 x 10¯4. Calculate the pH of 0.0100 M solution of HF. If you solve this by the approximate method, you will exceed 5% by quite a bit (it'
just how much the measured value is likely to deviate from the unknown, true, value of the quantity. The art of estimating these deviations should probably be called uncertainty analysis, but for historical reasons is referred to as error analysis. This document contains brief discussions about how errors are reported, the kinds of errors that can occur, how to estimate random errors, and how to carry error estimates into calculated results. We are not, and will not be, concerned with the “percent error” exercises common in high school, where the student is content with calculating the deviation from some allegedly authoritative number. Significant figures Whenever you make a measurement, the number of meaningful digits that you write down implies the error in the measurement. For example if you say that the length of an object is 0.428 m, you imply an uncertainty of about 0.001 m. To record this measurement as either 0.4 or 0.42819667 would imply that you only know it to 0.1 m in the first case or to 0.00000001 m in the second. You should only report as many significant figures as are consistent with the estimated error. The quantity 0.428 m is said to have three significant figures, that is, three digits that make sense in terms of the measurement. Notice that this has nothing to do with the "number of decimal places". The same measurement in centimeters would be 42.8 cm and still be a three significant figure number. The accepted convention is that only one uncertain digit is to be reported for a measurement. In the example if the estimated error is 0.02 m you would report a result of 0.43 ± 0.02 m, not 0.428 ± 0.02 m. Students frequently are confused about when to count a zero as a significant figure. The rule is: If the zero has a non-zero digit anywhere to its left, then the zero is significant, otherwise it is not. For example 5.00 has 3 significant figures; the number 0.0005 has only one significant figure, and 1.0005 has 5 significant figures. A number like 300 is not well defined. Rather one should write 3 x 102, one significant figure, or 3.00 x 102, 3 significant figures. Absolute and relative errors The absolute error in a measured quantity is the uncertainty in the quantity and has the same units as the quantity itself. For example if you know a length is 0.428 m ± 0.002 m, the 0.002 m is an absolute err