Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Standard deviation.

  1. Dec 9, 2009 #1
    i would post this in the chem section but more people view this one..

    im having a quiz on standard deviation in chemistry lab onf riday, and im not sure AT ALL how to do this. i tried asking the teacher but hes not to good at explaining. and i tried lookinga t the difficult to understand book on this.
     
  2. jcsd
  3. Dec 10, 2009 #2

    Dale

    Staff: Mentor

    Do you not know the formula or do you know the formula but not know how to use it? If the latter, what part specifically are you having trouble with?
     
  4. Dec 10, 2009 #3
    nope i dont know ANYTHING. i ssaw the formula in class but was still confused b ut i dont even know the formula now i lost the note for it.
     
  5. Dec 10, 2009 #4
    This will get you started. This is the definition of the mean-squared deviation for n measurements:
    http://www.xycoon.com/mean1.htm
    The rms (or root mean squared) deviation is the square root of this.
    Bob S.
     
  6. Dec 10, 2009 #5
    thanks for the link bob!!
    but it was really easy, i asked my lab teacher today i cant believe i thought it was hard.

    now if only i could do the gas stoichiometry in ideal gas equations....
    i have been dealing with stoichiometry the entire semester, yet, i always forget things that ci ysed to know. for instance this is a 15 week semester, we are in week 14. i have been getting the highest grades on all the exams(its a gen chem 1 class) anyway, my teacher will be like, this unit will be easy for you, its just like limiting reagnt problems, and ill be like, oh i forgot how to do those (event hough we did them 2 weeks ago)
    i8 had a quiz today and i forgot how to use molarity even..

    when i get the quiz back ill probably post the question on here. does anybody have a good site to look at gas stoichiometry explanations? has anybody ever heard of students forgetting the materials so quickly.
     
  7. Dec 11, 2009 #6

    jtbell

    User Avatar

    Staff: Mentor

    We do have a chemistry forum here. (hint, hint :smile:)
     
  8. Dec 11, 2009 #7
    if i have any more questions ill post them there ;). any opinions on te paragraph i just quoted in your experience?s
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook