Ammonia early atmosphere

In a paper pnblished in the early 1950s Touster found that sodio derivatives of many alkyl-substituted heteroaromatic compounds or of allyl-substituted benzenes 30 can be oximated with alkyl nitrites in refluxing anhydrous liquid ammonia at atmospheric pressure... 

This requirement is fulfilled for electric discharges in a reduced atmosphere containing methane, ammonia, and water, as in the original Miller experiment. It has also been observed for atmospheres based on N2 and CO or CO2 on the condition that H2 or methane is also present in snfflcient amonnts (19). A neutral atmosphere (based on N2, CO2, and water) wonld produce much lower yields of organics (by several orders of magnitude). In the absence of other species to be oxidized, the rednction of CO2 reqnires the concomitant thermodynamically nnfavorable conversion of water into O2 (as in photosynthesis). However, even if the atmosphere was nentral when life arose, as nsnaUy believed, the Earth was not nniform with respect to redox state simply becanse the rednced state of the mantle and the high volcanic activity favored the occnrrence of locally rednced environments (for instance, in hydrothermal vents in the oceans). Then, a preservation of the hydrogen content of the early atmosphere or the diversity of environments on the early Earth is likely to have made amino acid formation possible, at least at specific places. 

In the years since Miller s experiment, ideas about the chemistry of life s origin have become more precise as a consequence of much experimentation and of exploration in outer space. We now know that the earth s primary atmosphere was formed mainly by degassing the molten interior rather than by accretion from the solar nebula. It seems likely that the main carbon sources in the earth s early atmosphere were CO2 and CO, not methane as assumed by Miller, and that nitrogen was present mainly as N2 rather than as ammonia. Repetition of Miller-type experiments with these assumed primordial atmospheres again gave biomolecules. 

Water (H2O), ammonia (NHj), methane (CH ), and nitrogen (N2) are present in the early atmosphere. The supply of cyan gas (CNjj, hydrogen cyanide (HCN), carbon monoxide (CO), and hydrogen (Hj) is also adequate. Amino acids and lipids are formed in large amounts. Subsequently, proteins are formed from amino acids and colloidal systans from lipids. Vesicles bounded by phospholipid bilayers turn out to be strong and reproducible. 

Methane may also have been essential to the formation of life. The early atmosphere on Earth was relatively rich in methane and ammonia (as are the current atmospheres of most of the outer planets). Given an energy source such as ultraviolet... 

Today, about 21% of Earth s atmosphere is composed of O2, but this was not always the case. Earth s early atmosphere was reducing (rather than oxidizing) and contained hydrogen, methane, ammonia, and carbon dioxide. About 2.7 billion... 

According to Le Chatelier s principle the equilibrium will be shifted to the right-hand side by high pressures and, since the reaction is exothermic, by low temperatures. Indeed early work by Haber showed that at 200 °C and 300 atmospheres pressure the equilibrium mix would contain 90% ammonia, whilst at the same pressure but at 700 °C the percentage of ammonia at equilibrium would be less than 5%. Unfortunately the activation energy is such that temperatures well in excess of 1000 °C are needed to overcome this energy barrier (Figure 4.1). The conclusion from this is that direct reaction is not a commercially viable option. 

As already mentioned, hydrogen cyanide is formed in simulation experiments using reducing primeval atmospheres. CN was discovered in interstellar space as early as 1940 by optical spectroscopy (Breuer, 1974), and later HCN itself (from measurements using millimetre wavelengths). Only a few years after the Miller-Urey experiments, Kotake et al. (1956) obtained HCN in good yields by reacting methane with ammonia over aluminium-silicate contacts ... 

Frank-Caro Also called the Cyanamide process. An early process for fixing atmospheric nitrogen. Lime and carbon were heated to produce calcium carbide this was reacted with nitrogen to give calcium cyanamide, which was hydrolyzed with steam to yield ammonia and calcium carbonate. Developed by A. Frank and N. Caro from 1895 at Dynamit, Germany, and used in Germany, Norway, and Italy until it was replaced by the Haber-Bosch process after World War I. 

A chemist designs an experiment to study the chemistry of the atmosphere of the early Ecirth. She constructs an apparatus to combine pure Scimples of the primary volcanic gases that made up the atmosphere billions of years c o carbon dioxide, ammonia, and water vapor. If the partial pressures of these gases are 50 kPa, 80 kPa, and 120 kPa, respectively, what s the pressure of the resulting mixture ... 

The atmosphere of modern Earth is thought to be very different from that of early Earth. Scientists conjecture that Earth s first atmosphere consisted of carbon dioxide, water vapor, nitrogen, and hydrogen sulfide, with trace amounts of ammonia and methane. The gases in the atmosphere are thought to have been released from the interior of the planet by volcanic eruptions. At this early... 

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