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#1 Re: Dark Discussions at Cafe Infinity » crème de la crème » Today 02:54:03

343) Henry Edward Armstrong

Henry Edward Armstrong, (born May 6, 1848, Lewisham, Kent [now a part of London], Eng.—died July 13, 1937, Lewisham), English organic chemist whose research in substitution reactions of naphthalene was a major service to the synthetic-dye industry.

Armstrong studied at the Royal College of Chemistry, where he developed a method of determining organic impurities (sewage) in drinking water, which was used in the sanitary surveys of water supplies and helped to control typhoid fever. In 1867, he went to study under Hermann Kolbe at the University of Leipzig in Germany and secured his Ph.D. there in 1870. In 187l he became professor of chemistry at the London institution Finsbury Circus (later Finsbury Technical College) and in 1879 was appointed to help organize the teaching of chemistry and physics at the City and Guilds of London institute. From 1884 he taught at the Central Technical College, retiring in 1911. He had been elected a fellow of the Royal Society in 1876.

Armstrong’s classic researches in chemistry dealt in part with subsitution in the hydrocarbon naphthalene, a problem on which he published some 60 treatises, which, with the work of his collaborators, securely established the chemistry of a substance and its derivatives that were of the greatest technical importance in the dyestuffs industry. He also pioneered in organic crystallography, contributed much to the understanding of the chemical composition of camphor and related terpene compounds, and devised a centric formula for benzene.

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#2 Re: This is Cool » Miscellany » Today 00:59:33

143) Aerosol container

Aerosol container, any package, usually a metal can or plastic bottle, designed to dispense its liquid contents as a mist or foam. This type of container was developed in 1941 by the American chemist Lyle D. Goodhue and others for dispensing insecticides. Since that time a wide variety of products ranging from disinfectants to whipping cream have been packaged in aerosol containers.

The most common type of aerosol container consists of a shell, a valve, a “dip tube” that extends from the valve to the liquid product, and a liquefied-gas propellant under pressure. The liquid product is generally mixed with the propellant. When the valve is opened, this solution moves up the dip tube and out the valve. The propellant vaporizes as it is released into the atmosphere, dispersing the product in the form of fine particles. In foam packs, such as shaving cream, the propellant and product are present together as an emulsion. On release, the liquid vaporizes, whipping the whole into a foam.

Chlorofluorocarbons, often called Freons, were used extensively as propellants in aerosol-spray products manufactured in the United States until 1978, when the federal government banned most uses of those compounds because of their potentially harmful environmental effect. Scientific studies indicated that chlorofluorocarbons released into the air rise up to the stratosphere, where they catalyze the decomposition of ozone molecules. The stratospheric ozone helps shield animal life from the Sun’s intense ultraviolet radiation, and it was feared that a significant reduction of atmospheric ozone by chlorofluorocarbons could lead to higher rates of radiation-induced skin cancer in humans.

In compliance with the federal ban, American and European manufacturers have substituted hydrocarbons and carbon dioxide for chlorofluorocarbons in most aerosol products. They also have developed aerosol containers that use air pressure produced by hand-operated pumps instead of a propellant.

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#3 Re: Ganesh's Puzzles » Oral puzzles » Today 00:43:37

Hi,

.

#4123. If the lines 2x + 4y + 5 = 0 and y = 2 + ax are parallel, find the value of 'a'.

#4 Re: Ganesh's Puzzles » 10 second questions » Today 00:37:14

Hi,

#6589. If a = 101, find the value of

.

#6 Re: Ganesh's Puzzles » Mensuration » Today 00:08:26

Hi,

M # 330. If the diagonal of a cube is

centimeters, then find the length  of its edge.

#7 Re: Ganesh's Puzzles » English language puzzles » Yesterday 15:24:47

Hi,

#2979. What does the verb (used with object) covenant mean?

#2980. What does the noun coverlet mean?

#8 Re: Ganesh's Puzzles » General Quiz » Yesterday 15:08:07

Hi,

#6991. Measuring one square kilometer in area, if the surrounding fields within the Merdeka Square are included, it is considered one of the largest squares in the world. At 75 hectares, it is over five times the size of Tiananmen Square, and 12 times the size of Place de la Concorde. Where is it?

#6992. Where is the 'Wembley Stadium'?

#9 Re: Ganesh's Puzzles » Oral puzzles » Yesterday 14:39:47

Hi,

.

#4122. Find the acute angle between the lines y = 2x + 5 and y + 3x + 2 = 0.

#10 Re: Ganesh's Puzzles » 10 second questions » Yesterday 14:29:22

Hi,

.

#6588. Find the value of

if
.

#11 Re: Ganesh's Puzzles » Series and Progressions » Yesterday 14:10:10

Hi,

SP#396. What is the sum of 100 terms of the series 1 - 2 + 3 - 4 + 5 - 6 + ....... ?

#12 Re: Ganesh's Puzzles » Mensuration » Yesterday 14:00:13

Hi,

M # 329. The three terminal edges of a rectangular solid are 36 centimeters, 75 centimeters, and 80 centimeters respectively. Find the edge of a cube (in centimeters) which will be of the same capacity.

#13 Re: Introductions » Hello there » Yesterday 13:43:37

Hi Raphael,

Welcome to the forum!

#14 Re: Ganesh's Puzzles » Oral puzzles » Yesterday 00:46:41

Hi,

.

#4121. Find the equation of a straight line which cuts the intercepts -3 unit and

units on x-axis and y-axis, respectively.

#15 Re: Ganesh's Puzzles » 10 second questions » Yesterday 00:35:46

Hi,

#6587. Find the value of

if
.

#16 Re: Ganesh's Puzzles » Series and Progressions » Yesterday 00:23:20

Hi,

.

SP#395. Find the sum of the given series : 1 + 2 + 3 + 4 + 5 + ...... + 5600.

#17 Re: Ganesh's Puzzles » Mensuration » Yesterday 00:12:32

Hi,

M # 328. 250 men took a dip in a water tank at a time, which is 80 meters x 50 meters.What is the rise in the water level if the average displacement of 1 man is 4 cubic meters?

#18 Re: This is Cool » Miscellany » 2018-06-21 22:09:28

142) Electroplating

Electroplating, process of coating with metal by means of an electric current. Plating metal may be transferred to conductive surfaces (metals) or to nonconductive surfaces (plastics, wood, leather) after the latter have been rendered conductive by such processes as coating with graphite, conductive lacquer, electroless plate, or a vaporized coating.

Figure 1 shows a typical plating tank containing copper sulfate (CuSO4) solution. A dynamo supplies electric current, which is controlled by a rheostat. When the switch is closed, the cathode bar, which holds the work to be plated, is charged negatively. Some of the electrons from the cathode bar transfer to the positively charged copper ions (Cu2+), setting them free as atoms of copper metal. These copper atoms take their place on the cathode surface, copperplating it. Concurrently, as shown in the drawing, the same number of sulfate ions are discharged on the copper anodes, thereby completing the electrical circuit. In so doing, they form a new quantity of copper sulfate that dissolves in the solution and restores it to its original composition. This procedure is typical of nearly all ordinary electroplating processes; the current deposits a given amount of metal on the cathode and the anode dissolves to the same extent, maintaining the solution more or less uniformly. If this balance is perfect and there are no side reactions or losses, a 100 percent cathode efficiency and 100 percent anode efficiency could possibly be realized.

If the metal surface of the cathode is chemically and physically clean, the discharged atoms of copper are deposited within normal interatomic spacing of the atoms of the basis metal and attempt to become an integral part of it. In fact, if the basis metal is copper, the new copper atoms will frequently arrange themselves to continue the crystal structure of the basis metal, the plate becoming more or less indistinguishable from and inseparable from the basis metal.

If suitable solutions of different metals are mixed, it is possible to plate a wide variety of alloys of metals. By this means plated brass can be made more or less indistinguishable from cast brass. It is also possible, however, to deposit alloys or compounds of metals that cannot be produced by melting and casting them together. For example, tin-nickel alloy plate has been used commercially for its hardness and corrosion resistance, which are superior to that of either metal alone. The deposit consists of a tin-nickel compound (Sn-Ni) that cannot be produced in any other way.

Other common alloy plates include bronze and gold, with varying properties, such as different colours or hardnesses. Magnetic alloy plates of such metals as iron, cobalt, and nickel are used for memory drums in computers. Solder plate (Sn-Pb) is used in printed circuit work.

Development Of Electroplating

While some metal coating procedures date back to ancient times, modern electroplating started in 1800 with Alessandro Volta’s discovery of the voltaic pile, or battery, which made noteworthy quantities of direct current electricity available. At about the same time, the battery was employed to deposit lead, copper, and silver. After a nodule of copper had been deposited on a silver cathode, the copper could not be removed. In the same year, zinc, copper, and silver were deposited on themselves and on a variety of basis metals (the metals on which the plating is applied), such as gold and iron.

Electroplating on a commercial scale was begun about 1840–41 and was accelerated by the discovery of cyanide solutions for plating silver, gold, copper, and brass. A cyanide-copper solution, for example, gave adherent deposits of copper directly on iron and steel. A cyanide-copper solution is still used for this purpose and also for the initial plating on zinc die castings. The copper sulfate solution described above corrodes these metals, giving nonadherent deposits.

Electroplating has become a large and growing industry with sophisticated engineering and equipment requirements. The metals that can be readily plated from aqueous solutions at high-current efficiencies near 100 percent can best be surveyed from Figure 2. It shows these metals in a single rectangle in their proper relationship to each other. The only metal shown outside the rectangle that is in common use is chromium, which is usually plated at low-current efficiencies of about 10–20 percent. Iron, cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, cadmium, tin, iridium, platinum, gold, and lead are more or less commonly used for plating. The others can be deposited easily but have not found much use in this way either owing to cost or availability or lack of useful properties.

The introduction of chromium plating in 1925 stimulated repercussions all through the plating industry. Chromium was essentially a bright plate and retained its brightness indefinitely. Chromium plate found a ready market in the automotive and appliance fields, in which the merits of the combination plate nickel-chromium or copper-nickel-chromium were soon proven. The requirements for closer control procedures in bath composition, temperature, and current density were reflected in better control and development of other processes.

So-called hard-chromium plating likewise created a new way of improving the wear resistance of machine parts and improving their operation owing to good frictional and heat resistance properties. Worn or undersized parts were built up with chromium plate.

While nonmetallic materials have been plated since the mid-19th century, a period of rapid growth in the utilization of electroplated plastics began in 1963 with the introduction of ABS plastic (acrylonitrile-butadiene-styrene), which was readily plated. The plastic part is first etched chemically by a suitable process, such as dipping in a hot chromic acid–sulfuric acid mixture. It is next sensitized and activated by first dipping in stannous chloride solution and then in palladium chloride solution. It is then coated with electroless copper or nickel before further plating. A useful degree of adhesion is obtained (about 1 to 6 kg per cm [5 to 30 pounds per inch]) but is in no way comparable to the adhesion of metals to metals.

Principal Applications

Copperplating is used extensively to prevent case hardening of steel on specified parts. The entire article may be copperplated and the plate ground off on the areas to be hardened. Silver plating is used on tableware and electrical contacts; it has also been used on engine bearings. The most extensive use of gold plating is on jewelry and watch cases. Zinc coatings prevent the corrosion of steel articles, while nickel and chromium plate are used on automobiles and household appliances.

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#19 Re: Ganesh's Puzzles » English language puzzles » 2018-06-21 16:53:02

Hi,

#2977. What does the adjective couture mean?

#2978. What does the noun cove mean?

#20 Re: Ganesh's Puzzles » General Quiz » 2018-06-21 16:39:07

Hi,

#6989. According to the World Meteorological Organization's (WMO), the highest temperature ever recorded was 56.7 °C (134.1 °F) on 10 July 1913. Where is it?

#6990. Name the tallest statue in the world.

#21 Re: Ganesh's Puzzles » Oral puzzles » 2018-06-21 16:18:11

Hi,

#4120. Find the equation of a line passing through the points (-1,5) and (2,7).

#22 Re: Ganesh's Puzzles » 10 second questions » 2018-06-21 16:09:58

Hi,

#6586. Find the value of

if xy + yz + zx = 11 and
.

#23 Re: Ganesh's Puzzles » Series and Progressions » 2018-06-21 15:50:28

Hi,

.

SP#394. Determine the sum of 6th and 19th term of the Arithmetic Progression 4, 9, 14, ....., 119 with 24 terms.

#24 Re: Ganesh's Puzzles » Mensuration » 2018-06-21 15:40:02

Hi,

M # 327. A cube of 384 square centimeters surface area is melt to make 'x' number of small cubes each of 96 square millimeters surface area. What is the value of 'x'?

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