Chunk effect

The most striking results were obtained with aehromatedZn-Fe alloy (0.3% Fe). It was confirmed that the particularly good corrosion resistance of this alloy is due to the properties of the chromating layer,which remained firmly attached to the metal surface until nearly all of the zinc alloy had been dissolved. This feature rules out chunk effects, so that a shift in the ratio of EC to CMT measurements from a little less than one to one half (over a long time and accompanied by an increase in corrosion potential by 120 mV) could best be explained as a result of a shift in... 

A second major type of reactor involves thermal destruction of the calcium carbide. At about 1,S00°F, both calcium carbide and acetylene are thermally oxidized. Therefore, a system such as a rotary kiln could be used for thermal destruction of the reactivity characteristics. The additional benefit of thermal destruction is that it will also effectively deal with potential sulfide reactivity problems. Large chunks of metals often included in the desulfurization slag will tend to be a problem for many types of thermal units. Concern over air emissions and cost are other hurdles to the use of thermal systems for calcium carbide desulfurization slag. 

The first step in the procedure calls for weighing out some chocolate and extracting fat from it by dissolving the fat in a hydrocarbon solvent. Fat needs to be removed because it would interfere with chromatography later in the analysis. Unfortunately, if you just shake a chunk of chocolate with solvent, extraction is not very effective, because the solvent has no access to the inside of the chocolate. So, our resourceful students sliced the chocolate into small bits and placed the pieces into a mortar and pestle (Figure 0-1), thinking they would grind the solid into small particles. 

But how can this acidification be effected without adding large amounts of strong acid (recall that permanganate is unstable in concentrated acid) Simple Dissolve the potassium manganate/potassium hydroxide mixture in water, throw in a few chunks of dry ice, and in the witches cauldron effect, watch the solution turn from green to deep purple ... 

Just as you don t train to run a marathon by waiting until the last minute and then running twenty miles a day for five days before the race, you cannot effectively prepare for the GRE by waiting until the last minute to study. Your brain works best when you give it a relatively small chunk of information, let it rest and process, and then give it another small chunk. 

Dry ice is perhaps the most common example of sublimation in everyday life. You may have seen this smoking white chunk of ice in a Halloween party punch or at a magic show with special effects. Deposition occurs in nature when cold temperatures freeze gaseous water vapors in the air directly into solid ice crystals commonly called frost. 

Effects of Surface Area Consider a single large block of ice melting. Will it melt faster than a set of smaller ice cubes of equal mass People who want the ice in their coolers to melt more slowly will use a larger block of ice. A larger block of ice has less surface area, and thus less of the ice is exposed to the warmer temperatures present in the cooler. Smaller ice cubes of the same mass will melt faster because they collectively have more surface area exposed. Chemists often avoid putting whole chunks of salts in their reactions. To increase the speed of the reaction, the solids are chopped up into a finer powder rather than left as larger pieces. 

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