Video

Explosions

Despite their seemingly random effects, explosions are actually predicable chemical reactions.  The website used as the primary source for this blog, emphasizes the importance of planning and data to achieve a desired result.

Thermodynamics is the key to an explosion.  It is crucial to know exactly how much energy is released.  Explosions are exothermic reactions, a endothermic reaction (requiring energy) would serve little purpose.  In mining, a too powerful explosion can threaten the safety of humans in the area.  A weak explosion would fail to expose the desired substances.  Blasting professional must have an estimate of a substance’s heat capacity.  The same explosion won’t yield the same result if the blasted substances are different.  Enthalpy is a useful statistic to know, because if too much energy is released, it can cause the following explosions to be triggered in a unwanted, perhaps dangerous way.  However, it seems that what really mattered to the blasting professionals was the energy released as a vibration.  Although vibrations haven’t yet been discussed in class, the vibration energy is still linked to thermodynamics and the total enthalpy of the system.

Did you know Mount Rushmore was crafted using explosives? See this link.

Sources:

http://www2.estrellamountain.edu/faculty/farabee/biobk/biobookener1.html

www.miningknowhow.info/glossary-of-terms/blast-vibrations

Featured image: http://fr-minecraft.net/news-minecraft-494-snapshot-12w37a.html

“Cool” Chemical Reactions

I find it ironic that an article titled “chemical reactions” actually had demonstrations that were not technically chemical reactions.  I suppose “Cool things that have to do with chemistry” doesn’t have the same ring to it.

(I’ll be going in reverse order, click here to see the original article)

  1. This one was a chemical reaction, the constant changing of color was due to the varying levels of the compounds in the solution.  The equation summarizing this would be IO3 + 2H2O2 + CH2(COOH)2 + H+ → ICH(COOH)2 + 2O2 + 3H2O.  This is a complex redox reaction.
  2. The ignition of the thermite is a reaction. Fe2O3 + 2Al → 2Fe + Al2O3 + heat and light.  It is a single replacement reaction, and the Iron is reduced.  However, the reaction with the liquid nitrogen was just a display to if the temperatures canceled out, rather than a chemical reaction.
  3. This is not a reaction, a change in the state of matter is not a chemical reaction.  If the helium was heated, it would still be helium
  4. Once again, not a reaction, because the Sulfur hexaflouride’s chemical makeup remains the same, despite its zany effects on human vocal chords.
  5. Just because a compound is absorbent, doesn’t mean there is a chemical change.  It is a little like an aqueous solution.  The water remained water throughout the video.
  6. This one was tricky, because the sodium acetate dissociated into the water solution.  Therefore, no chemical reaction took place.
  7. Not a reaction, the demonstration only took advantage of diamagnetism, a physical property.
  8. This was a decomposition reaction.  Oxygen gas was released and oxidized.  2KClO3(heat) → 2KCl + 3O2
  9. This was obviously a reaction.  The magnesium reacted with the oxygen in the carbon dioxide.  In the combustion reaction, the magnesium was oxidized.  2Mg + CO→ 2MgO + C
  10. This demonstration consisted two reactions.  The first was with the sodium and water.  It was a redox reaction, and the sodium was oxidized.  2Na +  2H2O → 2NaOH  +  H2   The heat from the first reaction triggered the second reaction with the sodium and chloride.  The second one was a combination reaction.  2Na  +  Cl2 → 2NaCl

Personally, my favorite reaction was with the Potassium chlorate and the gummy bear (#8).  I felt a combination of dread and amusement as I watched the gummy bear’s demise in the merciless inferno of chemical doom.

Sources:

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