Drano - Crystal Drano

Crystal Drano

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

The colored crystals in Drano are for appearance only; lye is white in color. Lye decomposes most organic matter and is particularly effective on fat and grease and hair which are materials which often clog drains. As the decomposition is more rapid if the temperature of the mixture is higher, and lye reacting with aluminum produces heat, shards of aluminum are an ingredient in Drano. Several chemical reactions take place here:

1. When Drano 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. (The result of lye reacting with fat is a kind of soap, sodium stearate, the same soap that was commonly made at home and also manufactured commercially in the 18'th and 19'th centuries.)
2. The formula for the lye reacting with the aluminum shards is 2NaOH + 2Al + 2H₂O ? 3H₂ + 2NaAlO₂, although the exact species in solution may be NaAl(OH)₄. The reaction can raise the temperature sufficiently to cause the mixture to boil. The reaction also liberates hydrogen gas which churns the mixture and improves the interaction between the lye and the materials clogging the drain. While the position of the mixture in the drain pipe usually does not result in high pressure developing from the liberated hydrogen or the boiling of the mixture, it is possible for the mixture to spurt out of the drain so the user must exercise care when using Drano.
3. The sodium nitrate "absorbs" the hydrogen, reducing the fire and explosion hazard posed by free hydrogen gas. Hydrogen combines with the nitrate ion, producing ammonia, which also decomposes organic material although not as aggressively as lye does. The reaction is: 2NO₃- + 9H₂ ? 2NH₃ + 6H₂O.

Crystal Drano was invented in 1923 by Harry Drackett. Bristol-Myers bought the Drackett Company in 1965 and sold it to S.C. Johnson in 1992.

For years, Drackett advertised Once every week, Drano in every drain. Various mixes of relatively non-toxic solvents are now sold commercially for the purpose.