Define uncertainty, Chemistry

Assignment Help:

This brings us to one thing that uniformly drives students crazy. When anything is measured in the lab, you must keep track of how accurately you can measure it. If you measure your licorice with a ruler, you can pretty easily tell how many centimeters long it is. With a little more effort, you can measure to the nearest tenth of a centimeter. One rule of thumb is that no matter how hard you try, you can only measure to the smallest division on your measuring instrument - in this case 0.05 cm with a ruler marked in tenths of cm, millimeters. This would mean that you are fudging and I will immediately know it if you tell me your licorice is 13.5762 cm long. You cannot measure closer than 13.55 0.05 cm with any accuracy with a standard wooden ruler marked in tenths of cm. It does not mean there is no possible way you can get a measurement with this many significant digits - you do need a better instrument to measure with though. In the following example we have claimed a slightly better accuracy than the rule of thumb given - this is as close as I would want to stretch it.

138_Uncertainty.gif

When you make more than one measurement of a length you are not changing the accuracy of your instrument (smallest division on your ruler) but you can change the precision of your measurement because by repeating the measuring process. When you carefully repeat a measurement several times, you are eliminating the possibility that, for example, you take a poor reading because you forgot to line up the end of the licorice with the 0 on the ruler well. So you are often encouraged to take measurements several times and average the results. Hint - if one measurement seems really different than what you might expect, try measuring it again. This is one of the quickest and least frustrating ways to catch errors in lab, hopefully before you leave for your next class.


Related Discussions:- Define uncertainty

Moisture removal in foods by different drying techniques, Q. Moisture remov...

Q. Moisture removal in foods by different drying techniques? To carry out the moisture removal in foods by different drying techniques. • make yourselves familiarized with

Spectroscopy, Spectroscopy: 1. Run IR spectra on both of your purified...

Spectroscopy: 1. Run IR spectra on both of your purified products and on pinacolone. Comment on any features of interest, including the C=O stretch frequencies. 2. Obtai

Acidity determination, 20ml of water sample requires 15ml of 0.1mg/l sodium...

20ml of water sample requires 15ml of 0.1mg/l sodium carbonate using phenolphthalein indicator. state the type of acidity and calculate the acidity

What are distinguishing characteristics of metallic bonding, What are disti...

What are distinguishing characteristics of metallic bonding?  Metallic  state  can  be  visualized  like an  array  of positive  ions,  with  a  common  pool  of electrons to

Mechanism of Picric acid, how we synthesis picric acid why it required 1 ho...

how we synthesis picric acid why it required 1 hour for the reaction with HNO3,H2SO4 and show the mechanism of picric acid and uses of picric acid. and what is the role of HNO3,H2S

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd