Natural boron is used in control rods for nuclear reactors, but commercial operators often enrich the boron to increase the proportion of the neutron-absorbing isotope.
Two mass spectra are obtained under identical operating conditions.
Natural boron sample:
• Peak at m/z = 10.0 with intensity 20.0 units
• Peak at m/z = 11.0 with intensity 80.0 units
Enriched boron sample:
• Peak at m/z = 10.0 with intensity 5.0 units
• Peak at m/z = 11.0 with intensity 95.0 units
Assume all peaks arise from singly charged monatomic ions.
(a) For the natural sample, calculate the percent abundance of each isotope.
(b) For the enriched sample, calculate the percent abundance of each isotope and determine by how many percentage points the lighter isotope has been reduced relative to the natural sample.
(c) Compute the average atomic mass of the enriched boron to four significant figures.
(d) Describe how the shift in average atomic mass could be used as a quality-control metric for assessing enrichment level in reactor-grade boron. Include a brief discussion of one limitation of this metric.