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Silicates and aluminates

Assignment 7, due on Nov. 20

Problems

All diagrams must be hand drawn, no photocopies or computer images will be accepted.

  1. Show that when two oxygen atoms of SiO44- units share with other SiO44- units, the silicates form a ring or an infinite chain.

    Show also that the stoichiometry of these silicates becomes (SiO3)n2n-.

  2. Draw an infinite double silicate chain structure that will be consistent with the stoichiometry Si2O5.

    Double chain silicates are called amphiboles. What is the stoichiometry for the type of double chain silicates shown in Inorganic Chemistry by Swaddle (a diagram is also shown on the web site)?

  3. What type of silicates is usually known as asbestos?

    What mineral is the most commonly sold asbestos? Describe its structure feature.

    What are the concerns in applications of asbestos?

  4. The sodium form of a synthetic zeolite A has a formula Na12[(AlO2)12(SiO2)12.27H2O. The city-supplied water has a hardness equivalent to 200.0 ppm of dissolved CaCO3. Assume 100% of the sodium ions exchange with the calcium ions in a water softener. If the water softener contains 2.19 kg of zeolite A, how much water shall be allowed to pass the water softener between regenerations of the zeolite A using a 6.0-M NaCl solutions?

    An effective operation is to have 67% of the sodium ions replaced by calcium ion in a water softener. How much water shall be allowed to pass the water softener between regenerations of the zeolite A?

    If, on average, 25.0% of the sodium ions from a 6.0-M NaCl solution replace the calcium ions in the zeolite during the regenration process, how much 6.0-M NaCl solution should be used each time for the regeneration of the zeolite in the water softener? Assume that all the calcium ions are replaced by sodium ions.

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