If this is the formula for a 2:1 phyllosilicate: (Si61 Alx)(Al3.2 Mg)yO20(OH)4 i) Determine values of x and y ii) Determine the amount of isomorphic substitution in the tetrahedra... If this is the formula for a 2:1 phyllosilicate: (Si61 Alx)(Al3.2 Mg)yO20(OH)4 i) Determine values of x and y ii) Determine the amount of isomorphic substitution in the tetrahedral and octahedral sheets iii) Calculate the charge on the clay mineral iv) Determine the equivalent amount of Ca that would be required to neutralize the charge on the clay mineral? If the phyllosilicate in Qn.1a above is montmorillonite, briefly explain how its presence would result in natural fertility but not necessarily the productivity of the soil. Briefly explain any two ways in which negative charges on the surfaces of clays are important to soil fertility and environmental protection.
Understand the Problem
The question is asking us to solve a practical problem related to soil mineralogy and chemistry. Specifically, it requires determining certain values related to the chemical formula for phyllosilicate minerals and explaining concepts related to soil fertility and environmental protection.
Answer
x and y are determined by balancing charges and substitutions; Ca neutralizes the imbalance. Montmorillonite has high CEC but may lack nutrients for productivity. Negative charges aid fertility and environmental protection through cation exchange.
The values for x and y are calculated by equating the total cation numbers to the base formula of a 2:1 phyllosilicate. Isomorphic substitution is based on Al replacing Si in tetrahedral sites and Mg in octahedral sites. The charge is calculated from the imbalance in substitutions. Ca is estimated by balancing calculated charge with calcium equivalence. Montmorillonite improves nutrient availability due to high CEC but doesn't necessarily enhance productivity without other nutrients. Negative charges facilitate nutrient and pollutant retention via cation exchange.
Answer for screen readers
The values for x and y are calculated by equating the total cation numbers to the base formula of a 2:1 phyllosilicate. Isomorphic substitution is based on Al replacing Si in tetrahedral sites and Mg in octahedral sites. The charge is calculated from the imbalance in substitutions. Ca is estimated by balancing calculated charge with calcium equivalence. Montmorillonite improves nutrient availability due to high CEC but doesn't necessarily enhance productivity without other nutrients. Negative charges facilitate nutrient and pollutant retention via cation exchange.
More Information
Montmorillonite's presence aids natural fertility due to its high cation exchange capacity (CEC), which improves nutrient availability. However, the absent nutrients or other limiting factors can hinder productivity. The negative charges on clays are significant because they hold nutrients via CEC and adsorb pollutants, aiding soil fertility and environmental protection.
Tips
Mistakes can occur when assuming equal substitution for isomorphic analysis. Ensure stoichiometric balance when calculating charge equivalences.
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