Potassium solar abundance

The Zag meteorite fell in the western Sahara of Morocco in August 1998. This meteorite was unusual in that it contained small crystals of halite (table salt), which experts believe formed by the evaporation of brine (salt water). It is one of the few indications that liquid water, which is essential for the development of life, may have existed in the early solar system. The halite crystals in the meteorite had a remarkably high abundance of 128Xe, a decay product of a short-lived iodine isotope that has long been absent from the solar system. Scientists believe that the iodine existed when the halite crystals formed. The xenon formed when this iodine decayed. For this reason, the Zag meteorite is believed to be one of the oldest artifacts in the solar system. In this lab, you will use potassium-argon radiochemical dating to estimate the age of the Zag meteorite and the solar system. 

Fig. 8.5. The delicious cocktail of the supernovas. Mixing 13 measures of SNll with 1 measure of SNl, we find a composition of matter that approaches observed abundances in the Solar System. Certain isotopes of chlorine, potassium and scandium, among others, are not produced in snfficient qnantities, however. (From Nomoto et at. 1997.)...

Calcium-41 decays to 4XK with a half-life of 1.03 x 105 yr (A, = 6.73 x 10-6yr-1). Calcium is a refractory alkaline earth element, while potassium is a moderately volatile alkaline element. Thus, calcium and potassium can be separated by both chemical and thermal processes. The short half-life of 41Ca means that the abundance in the early solar system was very low. Therefore, minerals with very high Ca/K ratios are required in order for the... 

K constitutes 93.26% of natural potassium. The elemental K abundance in the solar photosphere and in meteorites are in good agreement 3770 atoms of K per million Si atoms. This isotopic abundance is then... 

Potassium has been studied in stellar optical spectra. The famous red K lines at 7663 and 7697 A have been used. This pair of lines played a role in the history of K flame spectroscopy. As nucleosynthesis progressed the galactic K/H abundance ratio innewly born observed stars increased from 10 3 of solar in some early stars to a bitin excess of solar K/H today. If compared instead to Mg, the ratio K/Mg remains near the solar ratio in stars of all metallicities. This is understood as the coproduction of K and Mg in massive Type II supernovae. 

At only 2 percent abundance, the potassium content of Earths crust is much lower than the average measured in meteorites, most of which formed during the earliest stages of the solar system about 4.5 billion years ago. Since Earth formed at roughly the same time, the disparity means that some potassium-depleting process must have occurred as the planet evolved. Scientists have long speculated that much of the potassium may have moved into the molten outer core that surrounds the solid inner core of Earth. The molten core is composed primarily of... 

Most of the abundant anions and cations in both natural and marine waters — chloride, bromide, carbonate, sulfate, sodium, potassium, calcium, etc.—are transparent to solar radiation. Only a few trace metal cations, nitrite, and nitrate show any absorbance at all and their contribution to the total extinction is usually negligible in comparison to the organic species. 

REE patterns in bulk carbonaceous chondrites are fairly uniform, parallel to Cl, and show no dependence on volatility (e.g., no Eu or Yb anomalies). This uniformity also applies to the ordinary (H, E, EE classes) and enstatite (EL, EH classes) chondrite classes that show significant loss of their moderately and highly volatile elements (e.g., potassium, lead) and/or variations in their metal/silicate ratios. Accordingly, REE abundances in chondritic meteorites indicate no substantial cosmochemical fractionation (i.e., volatile related redox related) during their formation in the early stages of solar system evolution and indicate broad homogeneity in the solar nebula. 

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