Calcium hydroxide structure

Fisher, F. J. McCabe, J. F. (1978). Calcium hydroxide base materials an investigation into the relationship between chemical structures and antibacterial properties. British Dental Journal, 144, 341-4. 

Five pentosaccharinic acids were formed when D-xylose was treated with calcium hydroxide. This mixture included 2-C-methyl-D-threonic acid and 2-C-methyl-D-erythronic acid, the structures of which were... 

It was first obtained by Hertz [67] who proposed its use as an explosive, since (in the authors opinion) it develops greater explosive strength that PETN but is less sensitive. Tollens and Apel [68] have prepared the initial alcohol (m.p. 156°C) resulting from the reaction of acetone with formaldehyde in the presence of calcium hydroxide, to which they attributed the structure of an enneaheptitol anhydride without, however, determining which hydroxyl groups were dehydrated. 

The crystal structure of the natural mineral tobermorite was partly worked out by Megaw and Kelsey (22). Taylor and coworkers (15, 17, 26, 27) have carried out detailed investigations of tobermorite prepared synthetically, and correlated their structural features with those of the natural mineral structure. However, little was known about the nature of the surface, except what may be deduced from the surface energy results, the surface energy being approximately the geometric mean of the surface energies of calcium hydroxide and hydrous amorphous silica. 

Typically, a suspension of starch in water (35% of solids), containing a small quantity of bacterial alpha-amylase, and adjusted to a pH of 6.5 with slaked lime (calcium hydroxide), is drawn into a steam jet that raises the temperature almost instantaneously to 82.2°C (180°F). This temperature is maintained for 20 minutes, and then the liquor is drawn into a partially evacuated space where the liquor is cooled by evaporation to 60°C (140°F). The treatment with alpha-amylase and the cooling operations are continuous. It is sometimes desirable to heat the liquor under super-atmospheric pressure in between the treatment with alpha-amylase and the cooling, in order to break up small amounts of residual granule-structure which would interfere with refining operations at a later stage in the process. The treatment with alpha-amylase results in a cloudy liquor of 20 d.e., containing... 

It was stated that weakly crystallized tobermorite was synthesized in a mixture of calcium hydroxide and silica gel. The reaction is most efficient at the reagent ratio CaO Si02=5/6 and water-to-solid ratio 4 1. At short activation time, the formation of poor crystallized calcium silicates of B type with tobermorite-like structure was observed, Mechanochemically obtained tobermorite is stable till 800°C. Above this temperature, it... 

Advantages to this modified lignin include stable structure re-usable recovery of solvents for re-use high capacity, determined by the amount of calcium hydroxide used rapid effective in batch or column operations. 

Blast-furnace slag cements with high slag contents have lower heats of hydration than pure Portland cement, which is advantageous for large scale concrete structures (e.g. dams). The lower calcium hydroxide content results in their being somewhat more chemically stable than Portland cement. Blast-furnace slag cements are used in similar applications to Portland cement. 

Probably the rotary horizontal kiln is the most versatile, since it allows a feed of lumps or fines of limestone or marble, or wet or dry calcium carbonate sludges (Fig. 7.1). The main component of this calcination system is a 2.5- to 3.5-m diameter by 45- to 130-m long firebrick-lined inclined steel tube. Heat is applied to the lower end of this via oil, gas, or coal burners [7]. The feed to be calcined is fed in at the top end. Slow rotation of the tube on its axis gradually moves the feed down the tube, as it tumbles countercurrent to the hot combustion gases. In this way, wet feed is dried in the first few meters of travel. Further down the tube, carbon dioxide loss begins as the temperature of the feed rises. By the time the solid charge reaches the lower, fired end of the kiln it reaches temperatures of 900-1,000°C and carbon dioxide evolution is virtually complete. Normally the temperature of the lower end of the kiln is not allowed to go much above this as it reduces the life of the kiln lining. It also adversely affects the crystal structure of the lime product since it produces a dead-burned or overburned lime. Overburned lime is difficult to slake to convert it to calcium hydroxide and raises... 

A convenient laboratory method of preparing methane is to heat sodium acetate with soda lime, which is a mixture of sodium and calcium hydroxides. As organic acids or their salts are frequently used in the preparation of other compounds, it is well at this point to give a few facts about them. Acetic acid, which is described in detail in section 103, is the acid contained in vinegar. It has the structure represented by the formula... 

Crystal structure. Calcium hydroxide crystals have a hexagonal symmetry. The particles in commercial hydrated limes consist of micro-crystalline agglomerates. 

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