
Molality
(moles solute)/(kg solvent)

ppm
 (μg sample)/(mL solute)
 (mg sample) / (L solute)

When dealing with concentration problems, what are top three key things to think about?
 1) Density, concentration, molartiy... etc. of the solvent, solute and all else. Sometimes these do not correlate. Watch out for it!
 2) Think of when to use M1V1 = M2V2 rule. It is normally for getting a volume to a desired molarity. (Left side is moles taken from concentrated solution, and right side is moles placed in dilute solution)
 3) Think of it like a puzzle, or stoichiometry stuff :)

Kilo to pico
 Kilo (1000)
 Hecto (100  h)
 Deca (10  da)
 Deci (.1)
 Centi (.01)
 Mili (.001)
 Micro (.000001)
 Nano (.000000001)
 Pico (.000000000001)

What are the steps in chemical analysis?
 inject solution into chromatogram
 wash with solvent to flush it through column
 chromatogram separates analytes

What does it mean to mask an interfering species?
It means that a reagent is used that react with the interfering species, to prevent detection.

What is the difference between random and segregated heterogeneous material?
 Random: differences in composition, appear randomly and on a fine scale
 Segregated: large regions have obvious different compositions

ppb
 (ng sample) / (mL solute)
 (μg sample)/(L solute)

Calculating quantities of reagents needed to prepare solution
 M1V1 = M2V2
 (moles taken from concentrated solution) = (moles added to dilute solution)

Uncertainty in Addition and Subtraction from Absolute Values
e _{4} = √e _{1}^{2} + e _{2}^{2} + e _{3}^{2}
 e = uncertainty value
 absolute uncertainty = actual value
 relative uncertainty = wt% or fraction

Uncertainty in Multiplication and Division
e _{4} = √(%e _{1}) ^{2} + (%e _{2}) ^{2} + (%e _{3}) ^{2}
 e = uncertainty value
 You have to convert to relative uncertainty first!

Significant figure rule for ubcertianties
First digit of absolute uncertainty is the last significant figure of answer

Significant figures when taking log of something or solving log
 log339 = 2.530 (mantissa takes sig figs)
 10^{4.36} = 2.3 x 10^{4}

How are uncertainties in atomic masses obtained?
 2C = 2(12.0106 (± 0.0010))
 2C = 24.0210 ± 0.002
 4H = 4(1.00798 (± 0.00014))
 4H = 4.03192 ± 0.00028
So all the above uncertainties were multiplied by 2 then use the addition / subtraction rules to add them

How does the uncertainty change for a calibrated and uncalibrated pipet?
 Uncalibrated  multiply uncertainty by number of deliveries
 Calibrated  addition / subtraction rule

Coefficient of variation
Stdev expressed as a percentage of the mean value. Also known as the relative stdev.

What does it mean to find the area of a certian range?
Using the z chart, it is also the probablitity of measuring z in a certian range.
z = (x  x_{avg}) / s

Using the F test
Answers: Is s from the instrument "significantly" greater than s from original instrument.
 F_{calculated} = s_{1}^{2} / s_{2}^{2}
 The larger stdev is in the numerator.
If F _{calc} > F _{table} then there is a significant difference. This is because there is 5% probability of finding F above the table value. The significant difference means the null hypothesis is rejected and the values probably come from different populations.

Null Hypothesis
Two sets of data are drawn from populations with the same properties. There are no significant differences between populations.
Rejected if there is less than 5% probability of finding observed value.

Confidence Interval
Tool used to test probability of finding a range of values within a given location. You get t from a chart.
Just plug and chug the values in

Comparing a measured result with known result. Given:
set of values or mean
commercial value.
Calculate the confidence interval of 95% and then see if the commercial value agrees with it.

Grubbs test
To see if a value should be part of the measurements.
G_{cal} = (questionable value  avg) / stdev

How would your compare replicate measurements?
Found from F test (p.76)
 Significantly Different: use a more complicated it test that pools it all together
 Not Significantly Different: conduct a t test

