Carbon specks

J. S. Speck, M. Endo, and M. S. Dresselhaus, Structure and intercalation of thin bezene derived carbon fibers, J. Cryst. Growth 94, 834—848 (1989). 

When the sodium or potassium salt is available in a pure state, a known weight is ignited until only a residue of pure carbonate remains. A few drops of cone, sulphuric acid are then carefully added, and heat from a small flame applied until the excess of sulphuric acid is driven off. If any specks of carbon remain the last process is repeated. Finally the residue is weighed as alkali sulphate. 

PROBLEM 2.3 A small speck of carbon the size of a pinhead contains about 1019 atoms, the diameter of a carbon atom is 1.5 X 10 10 m, and the circumference of the earth at the equator is 40,075 km. How many times around the earth would the atoms from this speck of carbon extend if they were laid side by side ... 

The value of using atomic masses is that it allows us to count a large number of atoms by weighing a sample of the element. For instance, we can calculate that a small speck of carbon weighing 1.00 mg (1.00 X 10-3 g) contains 5.01 X 1019 carbon atoms ... 

Speck JS, Endo M, Dresselhaus MS. Structure and intercalation of thin benzene derived carbon fibers. / Cryst Growth 1989 94 834-848. 

This production of a peculiar degree of instability in the silver bromide, close to the atoms of sulphur in the sulphide, seems closely analogous to the other cases of promoter action, and the effects of a one-dimensional interface in a solid surface, which were considered in 3. It may be an effect of the same nature as the increased ease of decomposition of the calcium carbonate group, when this has calcium oxide groups adjacent to it. There is some evidence that the silver sulphide crystal lattice is rather more easily disorientated than the silver bromide, but since silver sulphide is, alone, not particularly sensitive to light, it seems certain that the sensitizing action of the sulphide speck must be due to a boundary action between the sulphide and the bromide.8... 

Place a drop of the concentrated test solution on a microscope slide. Introduce a few minute specks of sodium or ammonium carbonate. Some lithium carbonate crystals are formed immediately. Examine under the microscope (magnification 200 diameters) the crystals are in the form of either hexagonal stars or plates (compare CaS04.2H20, Section III.33, reaction 10). 

Next we pour some iron filings and some powdered sulfur into a large test tube and stir them together. The sample appears to be a dirty yellow, but if we look closely, we can see yellow specks and black specks. If we hold a magnet next to the test tube (Figure 1.3c), the black particles (with some yellow particles clinging to them) are attracted by the magnet. When we pour some carbon disulfide on the sample, the liquid turns yellow. We pour off that liquid and pour on more carbon disulfide until no yellow solid remains in the sample. When we evaporate the carbon disulfide in a fume hood, we get a... 

Further work [86] showed that the specific surface free energy of silver particles was the same whether they were evaporated on carbon or silver bromide, but was lowered by coating with gelatin. The latter is given as the reason for the stabilizing effect of gelatin on latent image specks. 

Note All of the metals present are now chlorides. Any silicon was dehydrated by the HCl to SiOj and will settle to the bottom of the beaker. The solution may have some color, depending upon the type of rubber. It usually will have a few white or gray particles floating on it, which are sulfur particles and possibly a few black specks, which are carbon particles that didn t get oxidized. It is not necessary to filter this. 

Molding areas should be equipped with positive pressure to keep out dust and airborne contaminants. Parts intended for the semiconductor industry are preferably molded in cleanrooms. Dust, oil, and particles of an organic nature must be prevented from contaminating the resin because during sintering they will carbonize into dark specks. 

Crystals, mp 35-36". bp(1 180°. Moderately sol in water sol In alcohol, chloroform, benzene. Practically insol in ether, petr ether. Takes up COa from the air and forms a crystalline carbonate. LDu i.p. in rats 370 mg/kg (Speck). 

Stalagtites and stalagmites are also found in hard water districts. When drops of calcium hydrogencarbonate solution collect on the roof of a cave, the solution decomposes, some of the water evaporates, carbon dioxide is lost and a tiny precipitate of calcium carbonate is left behind. Over many years these specks of calcium carbonate accumulate to form a stalactite. Solution that drips on to the floor undergoes the same decomposition, forming a stalagmite (Rg. 12.1). 

You have probably heard about, and looked at pictures of, the rings around the planet Saturn. On average, these rings are about twenty meters thick and they are made up of 93% ice and about 7% carbon. There is actually a pretty large distribution of particle sizes in these rings, ranging from specks the size of dust to chunks of material ten meters in... 

In propellants, increase in burning rate has been demonstrated by embedment of pieces of metal wires. They act physically by conducting the heat from the flame front deeper and faster into the propellant grain. In a somewhat similar vein, it has been found that radiative heat transfer in more or less translucent propellants can create hot spots in dark specks of impurities and thus cause erratic burning. This is of course undesirable. Uniform darkening of the grain by carbon black is the answer to this deficiency. 

A white solid - magnesium oxide - will be seen on the sides of the gas jar and black specks of carbon. 

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