Midterm Review

PLF: Cesar Rodriguez
E-mail: [e-mail]

Midterm Review Session

Chemistry 14BL
Midterm Review Session

*The information shown below is usually provided on the exam.
Also, remember that calculators can be used on the exam.*
Absolute Uncertainties
5.00 mL pipet: ± 0.01 mL
10.00 mL pipet: ± 0.02 mL
Digital balance: ± 0.2 mg
50.00 mL volumetric flask: ± 0.04 mL
100.00 mL volumetric flask: ± 0.08 mL
25.00 mL buret: ± 0.03 mL
Useful information pX = -logX pH = 14 – pOH
Kw = 1 x 10-14 pH = pKa + log[A-]/[HA] pKa + pKb = 14
Solution of quadratic equation of the form ax2 + bx + c is

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PLF: Cesar Rodriguez
E-mail: [e-mail]

Midterm Review Session
Measurements and Errors

1.) Consider the following three solutions:
Solution #1: A stock solution containing Al(OH)3 with a concentration of 5.17 x 10-7 M. The % relative error for this solution was determined to be ± 3%.
Solution #2: Prepared by pipetting 10.00 mL of solution #1 into a 50.00 mL volumetric flask and diluting to the mark with distilled water.
Solution #3: Prepared by pipetting 5.00 mL of solution #2 into a 100.00 mL volumetric flask and diluting to the mark with distilled water.
a.) What is the percent relative error for solution #3? Assume there is no error associated with the molecular weight. Look at screenshot.
2.) A laboratory procedure directs you to “Prepare 100 mL of a standard volumetric solution of a concentration of 0.2 M. What range of concentrations would give you the necessary precision of
0.1 %? Look at screenshot.

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PLF: Cesar Rodriguez
E-mail: [e-mail]

Midterm Review Session

3.)
A student in a laboratory prepared a standard solution of magnesium sulfate. The student first weighed out 0.5178 g of magnesium sulfate heptahydrate. The student transferred the solution quantitatively into a 100-mL volumetric flask. The student then added 5 mL of sulfuric acid together with 10 mL of distilled water into the