Calculate the molar solubility of Ag2 SO4 in (a) 0.22 M AgNO3 and (b) 0.22 M Na2 SO4 .( See Appe

Calculate the molar solubility of Ag2 SO4 in (a) 0.22 M...

Key Concepts

Molar Solubility

Molar solubility is defined as the number of moles of a solute that can dissolve in a liter of solution to reach a saturated state at a given temperature. It is directly influenced by the Ksp of the compound and any common ions present in the solution. Calculating the molar solubility involves setting up an equilibrium expression for the dissociation of the compound and solving for the solubility variable.

Equilibrium Expression Setup

Setting up an equilibrium expression involves writing the balanced dissolution reaction of the compound and expressing the Ksp in terms of the molar concentrations of the dissociated ions. This process requires identifying the stoichiometric coefficients, accounting for any initial concentrations provided by common ions, and solving the resulting equation to determine the molar solubility of the compound.

Solubility Product Constant (Ksp)

The Ksp is a specific type of equilibrium constant that applies to the dissolution of sparingly soluble ionic compounds. It represents the product of the molar concentrations of the constituent ions each raised to the power of its coefficient in the balanced dissociation equation. Understanding Ksp is crucial when calculating how much of a compound can dissolve in solution under equilibrium conditions.

Common Ion Effect

The common ion effect refers to the reduction in the solubility of an ionic compound when a solution already contains one of the ions present in the compound. This phenomenon occurs because the presence of a common ion shifts the equilibrium of the dissolving process, as predicted by Le Chatelier’s principle, leading to lower formation of the ion pairs necessary for further dissolution.

Transcript

00:01 Silver sulfate, or ag2 -s -4, has a ksp value of 1 .5 times 10 to negative 5th.

00:07 Let's start by writing out the equation for a saturated solution of ag2 -s -o -4.

00:14 So, ag2 -s -4, solid, partially dissociates to 2 -ag -plus plus, plus s -o -4 -2 -1, each of these in the equis phase.

00:33 So the ksp expression is the concentration of ag plus squared because of this coefficient of 2 times the concentration of so4 2 minus.

00:51 So we want to find the molar solubility of ag2 -s04 in 0 .22 molar a .g.

01:02 N .3 and 0 .22 molar n -a2 -s -o -4.

01:12 Let's start with our solution of 0 .22 -molar ag -n -o -3.

01:19 So we can write an ice table where our initial concentration of ag -plus is 0 .22 molar.

01:33 This comes from our ag -n -o -3 that begins in the solution.

01:40 We then start with 0 -molar s -o -4 -2 -1, and we could ignore.

01:45 Ag2 -s -o -4 in this table since it's a solid.

01:51 So our change is then some unknown x.

01:57 For so4 -2 -minus, it'll just be plus x, and for ag plus it'll be plus 2x since we have this coefficient of 2 out in front.

02:10 Our equilibrium is then just our initial plus our change.

02:14 So for ag2 plus that's 0 .22 plus 2x, and for s .o4 or 2 minus, it's just x.

02:24 And now we can plug these values into our ksp expression and solve for x.

02:34 So our ksp, 1 .5 times tenth and negative fifth, is equal to 0 .22 plus 2x squared times x.

02:47 Silver sold.

02:49 We can try making our small x assumption here, and if we do, we get the expression 1 .5 times 10 to the negative 5th is equal to 0 .22 squared times x...

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