In class, we learned the difference between accuracy and precision, which is especially important in chemistry. Accuracy is the proximity of a measurement to the true value of a quantity; whereas, precision is the proximity of several measurements to each other. In other terms, accuracy depends on the technique and precision depends on how reproducible the measurement is. A measurement with accuracy usually also has a component of precision. In chemistry, significant figures are used to show the value of something being measured. Significant figures include zeros that are between whole numbers, zeros at the end of a number if there's a decimal point, all numbers in scientific notation, and all nonzero integers. With these significant figures, we can estimate one digit past the calibration of the instrument being used for the measurement. When adding or subtracting significant figures, the answer is rounded to the smallest number of decimal places present in the equation; on the other hand, multiplication and division are rounded out to the smallest number of significant digits in the equation.
I found some helpful links for determining significant figures and using them in problems:
http://chemistry.about.com/od/mathsciencefundamentals/a/sigfigures.htm
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch1/sigfigs.html
http://chemwiki.ucdavis.edu/Analytical_Chemistry/Quantifying_Nature/Significant_Digits
Great post! I really liked how you explained the difference between accuracy and precision and the rules for determining significant digits. The only think I would have added would maybe be a chart to organize the rules!
ReplyDeleteThis really helped me know what significant figures are and how to tell when zeros are significant. I would have added an example just to clarify some points that you made about significant figures.
ReplyDeleteErin, I liked how you explained the difference between accuracy and precision. I know the two concepts can be very confusing and easy to mix up, and this will help others understand their meanings. In addition, the way you explained which digits are significant in a number in chemistry was very detailed and helpful. However, one thing I would have added was a picture of accuracy and precision together. A visual of the two terms could help someone further differentiate between the two. Also, consider including a couple examples of numbers, pointing out which digits are significant. This will allow the readers to see the different rules at work. Other than that, great post!
ReplyDeleteErin I really like the amount of detail you put into the definitions of the words you were explaining. You included a lot of different information but kept it relatively simple so the reader could still understand what you were trying to say. Next time maybe include a link to a website that has examples or even include a picture or video. Your definitions were great, it just helps some people to see the work for themselves as opposed to someone just telling them exactly what it is. This really helped, thanks again!
ReplyDeleteErin, I found your post very helpful remembering the rules to significant figures! You did a nice job going into detail with each point and rule you stated, which served as great help. Although, I would put a chart or organizer to show the rules more clearly.
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