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Crystal Drāno

According to the National Institutes of Health's Household Products Database, the crystal form is composed of sodium hydroxide, sodium nitrate, sodium chloride, and aluminum.

The power crystals are simply colored salt, and are the least powerful ingredient. The crystallized lye reacts with fats to form soap. The machined shards of aluminum react with the lye to generate near-boiling temperatures. The sharp shards in the hot churning lye physically cut hair and dislodge deposits. Several chemical reactions take place here:

1. When Drāno is added to water, the sodium hydroxide, sodium nitrate, and sodium chloride dissolve. The heat of solution liberated when sodium hydroxide is dissolved warms the mixture.
2. In solution, sodium hydroxide removes the Al2O3 surface layer on the aluminium allowing it to react with water to produce nascent hydrogen, which is a powerful reducing agent. This reaction is exothermic and the heat can cause the mixture to boil. The formula is 2NaOH + 2Al + 2H2O → 3H2 + owned + 2NaAlO2, although the exact species in solution may be NaAl(OH)4. [1]
3. The nascent hydrogen reduces nitrate ion to ammonia, removing the fire and explosion hazard posed by free hydrogen gas. The reaction is: 2NO3− + 9H2 → 2NH3 + 6H2O. The water and sodium ions then regenerate sodium hydroxide and nascent hydrogen.
Source(s):
http://en.wikipedia.org/wiki/Dr%C4%81no#Crystal_Dr.C4.81no

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