Solubility question (1 Viewer)

erucibon

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500mL of 0.027M AgNO3 and 500mL of 0.0030M KBrO3 are mixed, forming a precipitate of silver bromate.
Calculate the solubility product of silver bromate.
Calculate the solubility of silver bromate in mol/L.
Solid potassium bromate is soluble in water. What happens when a few crystals of potassium bromate are added to the solution containing precipitated silver bromate?

please help, thanks
 

jazz519

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So this is one of those advanced questions where it uses concepts from module 6 as well (i.e. the dilution formula C1V1=C2V2 because you are adding one amount of solution to another amount of solution)

First off write a chemical equation showing reaction of the initial chemicals

AgNO3(aq) + KBrO3(aq) --> AgBrO3(s) + KNO3(aq)

After this write a reaction showing equilibrium dissociation of the insoluble salt

AgBrO3(s) <--> Ag^+(aq) + BrO3^-(aq)

Write Ksp expression then

Ksp = [Ag^+][BrO3^-]

this is actually one of the questions where making a RICE table is not a good idea (because the dilution memes extra steps and hard to put it into a table)

First find diluted conc of AgNO3

C1V1 = C2V2
(0.027)(500) = C2(500+500)
C2 = 0.0135 M

From this find [Ag^+]

We can use [Ag^+] = [AgNO3] (concentration ratio works like a molar ratio)
[Ag^+] = 0.0135 M

Repeat this same thing for BrO3-

C1V1=C2V2
(0.0030)(500) = C2(500+500)
C2 = 0.0015 M

Now [BrO3^-] = [KBrO3]
[BrO3^-] = 0.0015 M

So sub in your numbers after this

Ksp = (0.0135)(0.0015) = 2.025 x 10^-5 (and correct for sig figs after)

b) Then for this treat like different q

AgBrO3(s) <--> Ag^+(aq) + BrO3^-(aq)

Ksp = [Ag^+][BrO3^-]
2.025 x 10^-5 = x^2 (make a RICE table to actually check this it's needed in working for marking criteria)
Solve for x
giving x = 4.5 x 10^-3 M
Which is ur molar solubility

c) This question is just a classic Le Chatelier's Principle one

AgBrO3(s) <--> Ag^+(aq) + BrO3^-(aq)

Adding KBrO3 the K+ is spectator and the BrO3- increases the [BrO3^-] concentration so shifts equilibrium left by Le Chatelier's principle which means less of your ions concentration and more precipitate i.e. solid forms
 

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