Author Archives: David Harvey

Titrimetic Analysis of Mixtures

Shown below is a titration curve for a mixture of two monoprotic weak acids, HA and HB, where pKa,HA = 4.00 and pKa,HB = 8.00.  The titrant is 0.200 M NaOH. (a) Briefly explain how you can tell that this … Continue reading

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Titration Curve for Amino Acid

Shown below is a potentiometric titration curve for a 0.050-g sample of an amino acid dissolved in water and titrated with 0.100 M NaOH. Based on this titration curve, answer the following questions: (a) How many titratable acid/base sites does … Continue reading

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Titrimetric Analysis of Amino Acids

The quantitative titrimetric analysis of amino acids often is complicated by the high pKa of the —NH4+ group, which produces a titration break that is too small for the effective use of a visual indicator. There are several ways to … Continue reading

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Complexometric Titration of CaO in Limestone: Analysis of Procedure

In the EDTA titration for CaO in limestone, the pH of the sample is made sufficiently basic so any magnesium thatis present will precipitate as Mg(OH)2. The adjustment of pH is fairly critical, as complications  arise if the solution is … Continue reading

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Gravimetric Method for Analysis of Phosphorous: Analysis of Procedure

Once upon a time, a common method for determining phosphorous was to convert it to phosphate, precipitate it as magnesium ammonium phosphate, MgNH4PO4, and ignite it to form magnesium pyrophosphate, Mg2P2O7.  The solubility reaction for MgNH4PO4 is MgNH4PO4(s) ↔ Mg2+(aq) … Continue reading

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Sampling Plan for Cadmium Leeching from Strip Mine

One of the hazards of strip mining is that water passing through the mine’s “tailings” (the piles of discarded material) is often very acidic and contains high concentrations of metal ions, such as Pb2+ and Cd2+. (a) Suppose you are … Continue reading

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Extraction and Analysis of Gingko Leaves

You may know that there is a growing interest in the ginkgo tree because herbal supplements using extracts of ginkgo are believed to aid in fighting memory loss.  A recent paper [Lang, G.; Wai, C. M. Anal. Chem. 1999, 71, … Continue reading

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Developing a Sampling Plan for Lead in Soil

When leaded gasoline was available, automobiles were a significant source of the total yearly environmental emission of Pb.  During internal combustion lead in gasoline, which was present as tetraethyl lead, was vaporized.  The lead, now present as Pb0, adsorbed to … Continue reading

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Separating a Weakly Acidic Analyte from a Weakly Basic Interferent

Imagine  you have an aqueous sample containing a weak acid analyte, HA, and a weak base interferent, HI.  The following information about HA, HI, the method of analysis, and the sample are available to you: Ka,HA = 1.00 x 10-3 … Continue reading

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Sampling M & Ms

Carry out the following “experiment” to test the validity of the sampling constant equation mR2 = Ks where m is the sample’s mass, R is the relative standard deviation for sampling, and Ks is the sampling constant. Obtain a package … Continue reading

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