Chapter 1 · Introduction

Problem set · Sharp, Principles of Stable Isotope Geochemistry, 1st ed. (2007) · Answers →

Problem 1

Comment on the following:

  1. Combined measurements of oxygen and phosphorus isotope ratios might be useful in tracing the movement of phosphate in the phosphorus cycle on Earth.
  2. Some of today’s scientists cite only the most recent papers in a field because the latest information on the subject is probably more reliable and most meaningful.
  3. Applications of stable isotope measurements are almost unlimited in fields related to biomedicine.

Problem 2

Calculate the difference in average velocities at constant temperature between the molecules 12C16O16O and 13C16O16O. What significance might this difference play in determining carbon isotope ratios of marine plants?

Scratch worksheet

Problem 3

Both Si and Se are present in diatoms and seawater. At a given temperature, would you expect the isotopic fractionation between diatoms and water to be larger for 29Si/28Si or for 80Se/78Se?

Worksheet

[Worksheet constructed; the isotope masses are from standard tables, not printed in the problem.]

Problem 4

  1. What do you conclude about the characteristics of bonds to H and D from the differences between solubilities of salts in H2O and D2O?
  2. Why should the boiling point of D2O be higher than that of H2O?

Problem 5

  1. The atomic weight of fluorine is 18.9984032 ± 0.0000005. The atomic weight of sulfur is 32.065 ± 0.005. Why is the atomic weight of fluorine known to such higher precision than that of sulfur?
  2. Calculate the atomic weight of boron, as listed in the periodic table. [Uses the isotope masses and abundances of Table 1.4 in the text.]
  3. What are the molecular weights of 12C16O16O, 13C17O16O, and 13C18O18O to six significant figures?

[Worksheets constructed; isotope masses as in Table 1.4 and standard tables.]

Transcribed from Z. Sharp, Principles of Stable Isotope Geochemistry, 1st ed. (Pearson Prentice Hall, 2007), end-of-chapter problem set (published source). Reference-scale names are written VSMOW, VPDB and VCDT where the original used SMOW, PDB and CDT, with the original numerical constants unchanged; historical usages (e.g. Craig's definition of SMOW) are kept as printed.

The source PDF's text layer scrambles mathematics, so equations and some values were reconstructed during transcription. Bracketed notes and anything tagged reconstructed or check vs print are editorial (constructed), not part of the original, and the warn-tagged items should be verified against the print copy.