Final Exam Quant Review

(moles solute)/(kg solvent)

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

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

• -inject solution into chromatogram
• -wash with solvent to flush it through column
• -chromatogram separates analytes

It means that a reagent is used that react with the interfering species, to prevent detection.

• Random: differences in composition, appear randomly and on a fine scale
• Segregated: large regions have obvious different compositions

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

• M1V1 = M2V2
• (moles taken from concentrated solution) = (moles added to dilute solution)

e₄ = √e₁² + e₂² + e₃²

• e = uncertainty value
• absolute uncertainty = actual value
• relative uncertainty = wt% or fraction

e₄ = √(%e₁)² + (%e₂)² + (%e₃)²

• e = uncertainty value
• You have to convert to relative uncertainty first!

First digit of absolute uncertainty is the last significant figure of answer

• log339 = 2.530 (mantissa takes sig figs)
• 10^4.36 = 2.3 x 10⁴

• 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

• Uncalibrated - multiply uncertainty by number of deliveries
• Calibrated - addition / subtraction rule

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

Using the z chart, it is also the probablitity of measuring z in a certian range.

z = (x - x_avg) / s

Answers: Is s from the instrument "significantly" greater than s from original instrument.

• F_calculated = s₁² / s₂²
• 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.

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.

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

Calculate the confidence interval of 95% and then see if the commercial value agrees with it.

To see if a value should be part of the measurements.

G_cal = (questionable value - avg) / stdev

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