Elemental ratios carbon

Surface treatment Lap shear (MPa) Ratio element to carbon ... 

If the sample is pure (this can generally be checked by thin layer chromatography or gas chromatography) then the elemental analysis values for carbon, hydrogen and nitrogen can be used to obtain element ratios, provided that C, H, N and 0 are the only elements present. 

Fig. 1. Heavy over light s-elements ratio versus metallicity. Lines are theoretical predictions for a 1.5M AGB stars with C/0=1.1 and three different choices for the neutron exposure rate (see Busso et al., 2001, ApJ, 557, 802). Black dots are for galactic carbon stars analyzed in Abia et al. (2002, ApJ 578, 817).

A simplified conceptualization of oceanic DOM pools based on a two-pool model showing carbon concentrations and elemental C N P ratios of the DOM pools. In reality, the reactivity of DOM probably spans a continuum that is presented herein as two pools, labile and refractory, for the purposes of simplification. Molar elemental ratios are in the format of C N P. Source-. From Hopkinson, C. S., and J. J. Vallino (2005). Nature 433, 142-145. 

When the peak intensity ratio Ij/lj is measured for each of all the elements observed (carbon, oxygen, chromium and nickel), the surface atomic concentration ratio nj/nj of the elements can be given by the following equation, if surface contamination is negligible ... 

Spectral intensities were measured as integrated peak area of each element and relative error for ratios of elemental intensity is about 10 % for aU elements except carbon. The adventitious surface carbon (contamination) was estimated at approximately 10% of the total carbon measured. The concentration of carbon is, therefore, supposed to be in relative error by ca. 20 %. 

Predicting how the atoms within molecules will bond with one another is a tricky endeavor because two nonmetals often can combine in multiple ratios. Carbon and oxygen, for example, can combine in a one-to-two ratio to form CO2 (carbon dioxide), a harmless gas you emit every time you exhale. Alternatively, the same two elements can combine in a one-to-one ratio to form CO (carbon monoxide), a poisonous gas. Clearly, having names that distinguish between these (and other) molecular compounds is useful. The punishment for sloppy naming can be death. Or at least embarrassment. 

As implied by their names, chondritic IDPs have roughly cosmic bulk compositions. Element ratios for hundreds of analyzed particles are roughly chondritic (data for CP IDPs are shown in Fig. 12.7) (Schramm et al., 1989). An exception, though, is carbon, which is significantly more abundant in IDPs. The mean carbon content of I DPs is 10 wt.%, relative to 3.2 wt.% for Cl chondrites (Bradley, 2004). The abundances of trace elements in bulk IDPs scatter from 0.3 to 3 times Cl, and volatile elements especially tend to be enriched (Flynn and Sutton, 1992). Higher abundances of carbon and of volatile elements, relative to the most solar-like carbonaceous chondrites, support the contention that IDPs are among the most primitive materials known. 

The analysis of petroleum feedstocks for the percentages of carbon, hydrogen, nitrogen, oxygen, and sulfur is perhaps the first method used to examine the general nature, and perform an evaluation, of a feedstock. The atomic ratios of the various elements to carbon (i.e., H/C, N/C, O/C, and S/C) are frequently used for indications of the overall character of the feedstock. It is also of value to determine the amounts of trace elements, such as vanadium and nickel, in a feedstock since these materials can have serious deleterious effects on catalyst performance during refining by catalytic processes. 

Pye, K., Blott, S. J., Croft D. J., and Carter, J. F. (2006). Forensic comparison of soil samples Assessment of small-scale spatial variability in elemental composition, carbon and nitrogen isotope ratios, colour, and particle size distribution. Forensic Sci. Int. 163, 59-80. 

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