Which Anion Precipitates First in a Pb(NO3)2 Solution?

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SUMMARY

The discussion centers on the precipitation of anions from a Pb(NO3)2 solution, specifically determining whether CrO4^2- or SO4^2- precipitates first when mixed with a 1.5×10−2 M solution of both anions. The concentration of Pb(NO3)2 is 0.55 M, which is crucial for calculating the solubility product (Ksp) for lead sulfate and lead chromate. The initial concentrations of the anions and the volume of lead nitrate added must be considered to find the Pb^2+ concentration at which the second anion begins to precipitate.

PREREQUISITES
  • Understanding of solubility product (Ksp) calculations
  • Knowledge of precipitation reactions in aqueous solutions
  • Familiarity with lead sulfate and lead chromate solubility products
  • Basic skills in titration and concentration adjustments
NEXT STEPS
  • Calculate the Ksp values for lead sulfate (PbSO4) and lead chromate (PbCrO4)
  • Learn how to perform titration calculations involving multiple anions
  • Study the effects of concentration changes on precipitation reactions
  • Explore the concept of selective precipitation in analytical chemistry
USEFUL FOR

Chemistry students, laboratory technicians, and educators involved in analytical chemistry or precipitation reactions will benefit from this discussion.

n.a.s.h
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Homework Statement




A solution is 1.5×10−2 M in both CrO4^2-and SO4^2-. To this solution, 0.55 M Pb (NO3)2(aq) is slowly added.

Which anion will precipitate first from solution?

a) CrO4^{2-}
b) SO4^{2-}

What is Pb^{2+} concentration at the point at which the second anion begins to precipitate?

Homework Equations





The Attempt at a Solution



k the thing that is confusing me is that the concentration of 0.55 M Pb (NO3)2(aq) was stated. Why is this relevant? because of that i do not know what to do
 
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Things will begin to ppt when the solubility product is reached. You know the value for the solubility product of both lead sulfate and chromate, you know the initial concentrations of the anions, you need to calculate the concentration of lead at each point in the titration. Don't forget to adjust the concentrations of the anions as you add volume from the lead nitrate solution.
 

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