Homework Help: Chemistry

Posted by MEG on Sunday, October 31, 2010 at 1:42pm.

Quantitative anaylsis of cl- ion is often performed by a titration with silver nitrate, using sodium chromate as an indicator. As standardized AgNo3 is addded, both white AgCl and red Ag2CrO4 precipitate, but so long as some cl- remains, the Ag2CrO4 dissovles as the mixgture is stirred, When the red color is permanent, the equivalence point has been reached.

a) calculate the equilibrium constant for the reaction:
2AgCl +CrO4=Ag2CrO4 +2Cl-

b)if 36.00cm^3 of 0.2200 m NaCl is mixed with 36.00cm^3 of 0.2200 m AgNO3, what is the concentration of Ag remaining in the solution?

Chemistry - DrBob222, Sunday, October 31, 2010 at 2:09pm
For a), use Hess' Law.
AgCl(s) ==> Ag^+ + Cl^-
Ag2CrO4(s) ==> 2Ag^+ + CrO4^-2

b)Since these are equal amounts of NaCl and AgNO3, this will be a saturated solution of AgCl(s) and the solubility is governed by the Ksp for AgCl.
AgCl ==> Ag^+ + Cl^-
Ksp = (Ag^+)(Cl^-)
Set up an ICE chart and solve for Ag^+/

Post your work if you get stuck.
Chemistry - MEG, Sunday, October 31, 2010 at 4:38pm
i dont understand how and why you use Hess's law to find the equilbiruim constant
Chemistry - DrBob222, Sunday, October 31, 2010 at 8:47pm
I will number the equations.
1) AgCl --> Ag^+ + Cl^- Ksp = ??
2)Ag2CrO4 ==> 2Ag^+ + CrO4^-2 Ksp = ??

Technically, I may not have named it right. Perhaps I should have said in a Hess' Law process.
Multilply equation 1 by 2 (which will make Ksp for AgCl squared.
Reverse equation 2 (which will mean the reciprocal of Ksp for Ag2CrO4. Then add the resulting two equations to obtain the equation the questions asks for, then Keq (what the problem wants) will be K^2(AgCl)*(1/K(Ag2CrO4).
Chemistry - MEG, Monday, November 1, 2010 at 6:27pm
i got part a right but i tried part b and i got an answer of 1.34 x 10^-5 but it was wrong

Answer this Question

Related Questions

chemistry - A chemist performed an experiment in which silver nitrate was used ...
chemistry - What is the silver ion concentration in a solution prepared by ...
chemistry - The traditional method of analyzing the amount of chloride ion ...
chem - 0.1802 g sample of a chlorocarbon compound was analyzed by burning in ...
chemistry - the value for the Ksp of silver chromate is reported to be 1.1 x 10...
chemistry - How do I balance this equation for silver nitrate and sodium ...
Chemistry - it takes 37.50 mL of 0.152 M sodium chromate to titrate 25.00 mL of ...
Chem - Solutions of sodium carbonate and silver nitrate react to form solid ...
DrBob222-Questions - Can you please check these for me. Thank you very much in ...
Chemistry - Silver(I) nitrate and sodium sulfate react to form silver(I) sulfate...

For Further Reading

First Name:
School Subject:
Answer: