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Lecture 6

# CHEM 212 Lecture Notes - Lecture 6: Potassium Hydrogen Phthalate, Desiccator, Sodium Carbonate

Department
Chemistry
Course Code
CHEM 212
Professor
Hamilton M.Coreen
Lecture
6

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Chem 212!
Lecture 6!
Sept. 20/2016!
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Stats overview:!
Conﬁdence Intervals --> mu= xbar+/- (ts/n^1/2)!1.
Comparing 2 sets of data --> two choices!2.
Grubbs Test --> Reject bad data!3.
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Comparing 2 sets of Data:!
"-Should you average each set of data?!
""-If its repeat measurements of the same thing, then you should average!
""-Don't average if you expect the data to be dierent!
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""""YES""""""""NO""""""""""""""""""""""""""""""""dbar= dierence average!
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"""F-Test on Sa/Sb"""""Calculate dierence for each pair of data!
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Passes (no sig. di)" " Fails (Sig di)!
""""""""""""Calculate dbar, Sd, use EQN with dbar and Sd!
""""""""""""!
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" " " " " " " " " " " " """""""""""""𝝂=no. of pairs -1!
t-test via EQN 1"""t-test EQN 2!
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uses S-pooled""""Requires calc for!
"𝝂=n1+n2-2" " " " 𝝂=("𝝂/N)-2 ******?!
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NEVER STOP AT AN F_TEST --> continue to T TEST!
Number of data sets in paired must be equal!
Number of data sets in unpaired do not have to be equal!
THEREFORE a hint for which pathway to choose !
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Quantiﬁcation:
Turn raw data into results!
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Sample: analyte in a matrix!
Matrix: Rest of the sample!
"Example. Measuring Fe in water versus in blood. !
Standard: pure chemical or solution of known chemical concentration!
Blank: reagent blank, method blank, instrument blank, ﬁeld blank, etc. Used to check for contamination. Analyzed
like an unknown sample. Everything but the sample.!
Blank really important when target concentration of what you are trying to me sure in your sample is very low. ppb!
QC or know sample: Has a known concentration of analyte. May may not have matrix!
Reference material: sample (has matrix) of known concentration of analyte. Buy from certiﬁed company \$\$\$\$!
!
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