Homework #4: Chemistry 100-Environmental Water ChemistryDue: February 10 20151) Draw the predominance diagram for aqueous fluoride species in a solution that contains0.001 moles/kg of dissolved fluoride (that is F=0.001 m) but has no dissolved aluminum.Before starting answer these questions:i) What is the mass balance equation for fluoride in this aluminum-free solution?ii) Is this system open or closed with respect to fluoride?2) Calculate a predominance diagram showing the solubility of gibbsite [Al(OH)3(s)] as afunction of solution pH by plotting the logarithm of the concentration of each aluminumspecies against pH assuming the solution is saturated with gibbsite. (Some hydrolysisspecies are left out to simplify the diagram.)Before beginning answer these questions:i) Is this solution open or closed with respect to aluminum?ii) If open what is the reservoir for aluminum?3) Now plot the same diagram showing the logarithm of aluminum species concentration asa function of pH for a solution in equilibrium with gibbsite but that also contains 0.001moles/kg of dissolved fluoride. Fluoride can form aluminum complexes via this reaction:AlF 2(aq) 3 H2O(l) = Al(OH)3(s) 3 H (aq) F-(aq)(Don’t assume that any other fluoride complexes of aluminum exist.coefficients).SpeciesGfo (kJ/mol)Al(OH)3(gibbsite s)-1156.5Al 3(aq)-489.5Al(OH)2 (aq)-698.3 -905.16Al(OH)2 (aq)-1104.43Al(OH)3o(aq)Al(OH)4-(aq)-1305.6H2O(l)-237.13 H (aq)0.0-157.24OH-(aq)HF(aq)-299.93F-(aq)-281.75-811.82AlF 2(aq)Ignore activity
