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Topic: Electrolytes and Precipitation  (Read 11602 times)

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Offline qchagurl327

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Electrolytes and Precipitation
« on: November 29, 2006, 04:31:32 PM »
Is each of the substances below a strong electrolyte? KF ,CH3Cl, H2O, NaOH, CH3COONa.. I think KF, NaOH, and CH3COONa are the strong ones, but i'm not sure whether CH3Cl is strong...

which of the following substances could be used to make a solution that is 0.1 M in Pb2+ ion.

a) Pb(ClO4)2
b) PbCl2
c) PbCrO4
d) PbCO3
e) PbS
f) Pb(NO3)2
I know that lead compounds are all soluble except for halogens, sulfates, sulfides, and sulfites...so would the answer be c,d and f?

AND I HAVE NO IDEA HOW TO FIGURE OUT THE BELOW 2 QUESTIONS.. SOMEONE PLEASE *delete me*!!!!!
Which of the following pairs of 0.1 M aqueous solutions would result in the formation of a precipitate upon mixing?
a) lead acetate + potassium hydroxide
b) ammonium acetate + cadmium nitrate
c) sodium chromate + nickel(II) iodide
d) strontium perchlorate + iron(II) sulfate

Which of the following pairs of 0.1 M aqueous solutions would result in the formation of a precipitate upon mixing?
a) lead acetate + potassium nitrate
b) sodium chromate + ammonium phosphate
c) nickel(II) nitrate + sodium sulfide
d) strontium perchlorate + iron(II) chloride
 

Offline DevaDevil

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Re: Electrolytes and Precipitation
« Reply #1 on: November 29, 2006, 05:21:56 PM »
Is each of the substances below a strong electrolyte? KF ,CH3Cl, H2O, NaOH, CH3COONa.. I think KF, NaOH, and CH3COONa are the strong ones, but i'm not sure whether CH3Cl is strong...


What type of bonds are there in CH3Cl?


I know that lead compounds are all soluble except for halogens, sulfates, sulfides, and sulfites...so would the answer be c,d and f?

a. Lead perchlorate is soluble
c. The solubility of PbCrO4 is about 1.34 x 10-7 mol/L at 25ÂșC, so no; 0.1M cannot be made
d. In general only alkali metals carbonates are soluble; lead is not an alkali metal, hence solubility is low
f. Nitrates are soluble indeed


AND I HAVE NO IDEA HOW TO FIGURE OUT THE BELOW 2 QUESTIONS.. SOMEONE PLEASE *delete me*!!!!!

look first to the combination of cation and anion that is the most insoluble
In case of the first example:
a) lead acetate + potassium hydroxide
Lead + hydroxide would form the insoluble Pb(OH)2, hence forming a precipitate.
« Last Edit: November 29, 2006, 05:48:07 PM by DevaDevil »

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