Indicate the correct answer:a) The high Si-O bond energy justifies the great stability and abundance of silica in nature.b) [SiO4]4- is the structural unit of isopolianions.c) Three-dimensional, lamellar and fibrous silicates consist only of [SiO4]4- tetrahedra.

The aluminium in a 1.2 g sample of impure NH4Al (SO4)2 was precipitated as hydrous Al2O3. The precipitate was filtered and ignited at 100° c to give anhydrous Al2O3 which weighed 0.1798 g. Calculate the % Al in the sample. (number of moles Al = 2; Al2O3 = 1)

What is the difference between chain and cyclic silicates?

a) Balance the following equation: K2CrO4+Na2SO3+HCl→KCl+Na2SO4+CrCl3+H2 b) In the process of oxidizing I− to I2, SO42− is reduced to SO2. How many moles of SO2 are produced in the formation of one mole of I2?

An impurity sometimes found in Ca₃(PO₄)₂ is Fe₂O₃, whichis removed during the production of phosphorus as ferrophos-phorus(Fe₂P). (a) Why is this impurity troubling from an eco-nomic standpoint? (b) If 50. metric tons of crude Ca₃(PO₄)₂ contains 2.0% Fe₂O₃ by mass and the overall yield of phospho-rus is 90.%, how many metric tons of P₄ can be isolated?

b To make NaTcO4, the metal is dissolved in nitric acid 7 HNO3 (aq) + Tc(s) → HTCO4(aq) + 7 NO2 (g) + 3 H20(2) and the product, HTCO4, is treated with NaOH to make NaTcO4. Write a balanced equation for the reaction of HTCO4 with NaOH. (Use the lowest possible coefficients. Be sure to specify states such as (ag) or (s). If a box is not needed, leave it blank.)

How can you separate alumina (Al2O3) from silica present in bauxite ore? Write the chemical equations for the reactions involved.

Tourmaline is the most colorful of all gemstones. It neutralizes negative forces and offers emotional stability. It is crystalline boron silicates compounded with metals such as Mg, Fe, Al, Na and Li.  The three most well-known minerals of tourmaline are: Elbaite                Na(LiAl2)Al6Si6O18(BO3)3(OH)4 Schorl                  Na(Fe3)Al6(BO3)3Si6O18(OH)4 Dravite                Na(Mg3)Al6(BO3)3Si6O18(OH)4   On a basis of 1000 kg of tourmaline rocks containing 25% Elbaite, 35% Schorl, 30% Dravite and 10% inerts, calculate the following: a)           kg Fe b)           total kg-atom O and kg-mol O2 in the three minerals c)           total number of Mg atoms in the rocks

Tourmaline is the most colorful of all gemstones. It neutralizes negative forces and offers emotional stability. It is crystalline boron silicates compounded with metals such as Mg, Fe, Al, Na and Li.  The three most well-known minerals of tourmaline are: Elbaite                Na(LiAl2)Al6Si6O18(BO3)3(OH)4 Schorl                  Na(Fe3)Al6(BO3)3Si6O18(OH)4 Dravite                Na(Mg3)Al6(BO3)3Si6O18(OH)4   On a basis of 1000 kg of tourmaline rocks containing 25% Elbaite, 35% Schorl, 30% Dravite and 10% inerts, calculate the following: a)           kg-mol Elbaite b)           % by wt BO3 in tourmaline rocks

Why is boron oxide often added to silica glass?