Street lamp

Although photochemical cycloadditions have gained acceptance in synthetic chemistry, most such reactions are limited to a relatively small scale. The use of a 1000-watt street lamp permits the irradiation of up to 1 mol of substrate in less time than 0.2 mol can be irradiated with the conventional 450-watt lamps. Thus, under optimum conditions, the submitters were able to add ethylene to 3-methylcyclohexenone on a 20-g scale in 48 hr (801) with a 450-watt lamp with the apparatus described here 94 g of this enone was condensed with ethylene in 8 hr (91%). 

The use of mercury for extracting precious metals by amalgamation has a long history and was extensively used by Spain in the sixteenth century when her fleet carried mercury from Almaden to Mexico and returned with silver. However, environmental concerns have resulted in falling demand and excess production capacity. It is still used in the extraction of gold and in the Castner-Kellner process for manufacturing chlorine and NaOH (p. 72), and a further major use is in the manufacture of batteries. It is also used in street lamps and AC rectifiers, while its small-scale use in thermometers, barometers and gauges of different kinds, are familiar in many laboratories. 

A sodium-vapor street lamp emits yellow light at wavelength A — 589 nm. What is the energy change for a sodium atom involved in this emission How much energy is released per mole of sodium atoms ... 

Eor example, street lamps use the emissions from excited sodium atoms, the dazzling colors of a fireworks display come from photons emitted by metal ions in excited states, and the red light in highway flares often comes from excited Sr ions. 

Romans mined the mineral cinnabar (HgS) from deposits in Spain 2000 years ago, and in the sixteenth century the Spanish shipped mercury obtained from the same ore deposits to the Americas for the extraction of silver. Mercury is an important component of street lamps and fluorescent lights. It is used in thermometers and barometers and in gas-pressure regulators, electrical switches, and electrodes. 

In 1792, Murdoch, a Scottish engineer, distilled coal in an iron oven and used the coal gas to fuel lamps in his home. This discovery led to the development of the coal gas industry, and by 1812, distilled coal gas was being used to fuel street lamps in London. Use of distilled coal gas quickly spread throughout Europe and remained an important source of domestic and industrial heating and lighting into the early twentieth century. 

Antoine Lavoisier, shown here with his wife, Marie-Anne, who assisted him in many of his experiments, was a concerned citizen as well as a first-rate scientist. He established free schools, advocated the use of fire hydrants, and designed street lamps to make travel through urban neighborhoods safer at night. To help finance his scientific projects, Lavoisier took part-time employment as a tax collector. Because of this employment, he was beheaded in 1794 during the French Revolution. Soon after his execution, however, the French government was erecting statues in his honor. 

Coal gas It is a mixture of many gases. It was used to light street lamps. 

Benzene was discovered in 1825 by Michael Faraday, who isolated it from the liquid that condensed from the gas that was burned in the street lamps of London. Although Faraday was able to deduce that the formula of benzene is C6Hb, it was not until 1866 that the correct structure was proposed by Kekule (see the Focus On box in Chapter 12 on page 469). 

What do gas discharge tubes have in common with street lights Do research to find out which gases are used in street lamps, and why certain gases are chosen for certain locations. 

So, rather than follow the example of Kauzmann s drunk [8], who searches for his keys under the light of the street lamp, despite having lost them in the dark, we have attempted over the past 15 years to shed new light on what he termed the darkness of pressure studies. ... 

Particles of sodium in the solid, liquid, and gas phases are shown. The atoms of gaseous sodium are much farther apart, as in a sodium vapor street lamp. 

To express optical rotation data in a meaningful way so that comparisons can be made, we have to choose standard conditions. The specific rotation, IoiJd, of a compound is defined as the observed rotation when the sample pathlength I is 1 decimeter (1 dm = 10 cm), the sample concentration C is 1 g/mL, and light of 589 nanometer (nm) wavelength is used. (Light of 589 nm, the so-called sodium D line, is the yellow light emitted from common sodium street lamps 1 nm = 10 m.)... 

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