1. The toxicity of mercury depends greatly upon the formulation of the metal. Which of them (elemental, metal ion, or methyl-mercury) is more likely to be absorbed through the skin? Explain your answer.
Lead(II) ions of Lead(II) nitrate reacts with chloride ion of NaCl to form a PbCl2 precipitate.
Pb2+(aq) + 2Cl-(aq) →PbCl2(s)
The precipitate of PbCl2 starts forming when the reaction quotient (Q=[Pb2+][Cl-]2) is greater than the solubility product of PbCl2.
The solubility product of PbCl2 is Ksp=1.17×10-5
To find the concentration of chloride ion that starts the precipitation of PbCl2, equate Q to solubility product and solve for the concentration of Chloride ion.
[Pb2+][Cl-]2 =1.17×10-5
[Cl-]2 =1.17×10-5[Pb2+]
[Cl-] =1.17×10-5[Pb2+]
[Pb2+] = concentration of lead(II) nitrate solution
[Cl-] =1.17×10-51.0×10-2=3.4205×10-2 M
The mass of NaCl needed to start the precipitation of PbCl2 is calculated below.
mass of NaCl =[Cl-]×Volume of solution ×Molar mass of NaCl
mass of NaCl =3.4205×10-2 M×800 mL ×58.44 gmol
mass of NaCl =3.4205×10-2 molL×800 ×10-3 L ×58.44 gmol
mass of NaCl =159915.216×10-5 g =1.599 g =1.6
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