Aluminum Sulfate Reacting With Sodium Hydroxide

7 03 2011

The Reaction of Aluminum Sulfate with Sodium Hydroxide



                  Aluminum Sulfate = Al(SO4)3               Sodium Hydroxide = NaOH   


Word Equation : Aluminum Sulfate + Sodium Hydroxide yields Aluminum Hydroxide + Sodium Sulfate


Al2(SO4)3 + NaOH -> Al(OH)3 + Na2(SO4)


Balanced Chemical Equation : Al(SO4)3 + 6NaOH -> 2Al(OH)3 + 3Na2(SO4)

 Visual Representation :Physical and Chemical Description Properties of Reactants : Aluminum Sulfate - Aluminum Sulfate can also be known as cake alum, fliter alum, and sulfuric acid. It has a melting point of 770 degrees celcius. It is slightly soluble in alcohol. Its has a pH level between 3.3 and 3.6, therefore it is acidic. Aluminum Sulfate is a solid, white crystalline and hygroscopic.  Hygroscopy is the ability to hold water molecules together by absorbing the material. Sodium Hydroxide - Sodium Hydroxide is also known as caustic acid. It is very ionic and contains sodium cations and hydroxide anions. The hydroxide anions make it a strong base which causes it to react with acids to produce water and other salts. It is a white solid, mainly in the form of granules, pellets and flakes. It has a melting point of 318 degrees celcius. Its pH level is 13 therefore it is a very strong base.How Reactants are Obtained : Millosevichite is a rare mineral with the formula Al2(SO4)3 (Aluminum Sulfate). It can be found in volcanic environments and is known for burning coal dumps. If something is anhydrous is means it contains no water, Aluminum Sulfate is rarely found as an anhydrous salt. Sodium Hydroxide is industrially produced as a 50% solution by variations of the chloralkali process. The choloalkali process is the seperation of a Sodium Chloride solution. Chlorine gas is also produced in the process of choloalkali. Solid Sodium Hydroxide is obtained from this solution by the evaporation of water. In 2004, the worldwide production of Sodium Hydroxide was about 60 million tonnes.

Conditions for Reaction to Occur : Both Aluminum Sulfate and Sodium Hydroxide are soluble. For the reaction we show them in the aqueous state. By mixing these two solutions together, it produces two new compounds, Aluminum Hydroxide and Sodium Sulfate. The Aluminum Hydroxide is considered insoluble and will therefore precipitate out as crystals. The Sodium Sulfate is soluble and will therefore remain dissolved and in solution.

Type of Reaction : Double Displacement.            Exampl  ——->

Physical and Chemical Description Properties of Products : Aluminum Hydroxide : Aluminum Hydroxide is found within nature as a mineral called gibbsite. Gibbisite has a typical metal hydroxide structure with hydrogen bonds. Aluminum Hydroxide is closely related to Aluminum Oxide Hydroxide and Aluminum Oxide, the only difference is loss of water. Aluminum Hydroxide forms gels that are the basis application of aluminum salts as flocculants in water purification. Aluminum Hydroxide is a white, non-crystalline powder. It is soluble in acids and alkali, and it’s acidity is 7 therefore it is neutral. It’s melting point is 300 degrees celcius. Sodium Sulfate : Sodium Sulfate is the sodium salt of sulfuric acid. It is a white crystalline solid and hygroscopic. It is very chemically stable and at high temperatures it can be reduced to Sodium Sulfide. It also has a pH of 7 so it is neutral. Sodium Sulfate has unusal solubility outcomes when in water. For example it tends to form double salts.

Uses for the Products of the Reaction : Aluminum Hydroxide : The yearly production of of Aluminum Hydroxide is about 100 million tonnes. Over 90% of that is converted to Aluminum Oxide which is used in the making of Aluminum Metal. Other uses of Aluminum Hydroxide are used as feedstock in the manufacturing of other Aluminum compounds such as : aluminium sulfate, polyaluminium chloride, aluminium chloride, zeolites, sodium aluminate, activated alumina, and aluminium nitrate. It is also used in the process of water purification, fire retardants, and antacids. Sodium Sulfate : Annually, 6 million tonnes of Sodium Hydroxide is produced, half from by-products of chemical processes and half from natural sources. The largest use is as a filler in home detergent powders. Also, it is used in the ‘kraft process’ for the manufacture of wood pulp. It is used in glass productions to remove small bubbles and scum formation, and in textile manufacture by reducing negative charge on fibres to help dye penetrate better. Also Sodium Hydroxide is used as thermal heat storage in tiles and an inert drying agent.

Significance of the Reaction to Industry Aluminum Hydroxide : Aluminum Hydroxide is used as a fire retardant which is useful in slowing the spreading of fires in buildings, automobiles, etc. For pharmaseutical uses, it is used as an atacid in the treatment of stomach disorders, this is somewhat declining as antacid use is decreasing due to increased use of acid blockers. It has also been used in some vaccine production, however, has been used less recently due to possible concerns as a contributing factor to alzheimers disease. Sodium Sulfate : Because the largest use of Sodium Hydroxide is used as a filler in powdered detergents, the world wide need is declining because more people are moving to concentrated, liquid detergents. Since so much of the production of Sodium Sulfate is just a by product of other useful processes, it is barely economical and because of industry changes its production is decreasing.

History : With Aluminum Sulfate, Sodium Hydroxide can be used to precipitate transition metal hydroxides. Aluminum Hydroxide is used as a gel floccilant to filter out particulate matter in water treatment. Aluminum Hydroxide is prepared at the treatment plant from Aluminum Suldate by reacting it with Sodium Hydroxide. Sodium Hydroxide has limited solubility. 
  Pauling, Linus (1970) Retrieved from Wikipedia from March 20-29
Earnshaw, Alan (1997) Retrieved from Wikipedia from March 20-29
Mallinckrodt Baker Inc provides info.


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