(a) ¿Precipitará Ca(OH)2 de una disolución 0.050 M de CaCl2 si se ajusta el pH a 8.0 ? (b) ¿Prec

step 1 This problem has two parts. In part one, we're asked if calcium hydroxide will precipitate from

(a) ¿Precipitará Ca(OH)2 de una disolución 0.050 M de CaCl2...

Key Concepts

Solubility Product (Ksp)

This concept refers to the equilibrium constant for the dissolution of a sparingly soluble ionic compound. It represents the product of the ion concentrations at saturation when the solid and its ions are in equilibrium. The Ksp allows us to determine whether a precipitate will form by comparing it to the reaction’s ion product under given conditions.

Reaction Quotient (Q)

The reaction quotient is calculated in the same way as the Ksp but using the current ion concentrations in the solution, prior to reaching equilibrium. By comparing Q to the Ksp, one can predict whether a precipitation reaction will occur: a Q greater than Ksp indicates that the solution is supersaturated and a precipitate will form, while a Q less than Ksp means the solution remains unsaturated.

pH Effect on Solubility

The pH of a solution can significantly influence the solubility of compounds that involve the hydroxide or hydrogen ion in their equilibrium. Adjusting the pH modifies the concentration of these ions (like OH– in the case of Ca(OH)2 formation), thereby shifting the equilibrium and affecting whether a precipitate is formed based on the solubility product conditions.

Stoichiometry of Precipitation Reactions

This concept involves the calculation of ion concentrations resulting from the mixing of different solutions. It requires accounting for dilution and the stoichiometric ratios between ions and the precipitate formed. Such calculations help determine if, after mixing, the ion product exceeds Ksp, thereby predicting the formation of a precipitate.

Transcript

00:01 This problem has two parts.

00:02 In part one, we're asked if calcium hydroxide will precipitate from a calcium chloride solution.

00:11 We are given the following information.

00:16 We have a ph of 8 .0 and we have a 0 .050 molar solution of calcium chloride.

00:38 Okay.

00:41 We know that the ksp, let me see what my ksp is here, for calcium hydroxide is 6 .5 times 10 to the minus 6th.

01:13 So what we're going to do is we are going to figure out what our ion product is for calcium hydroxide.

01:24 That's a two.

01:47 So what we have to do is figure out these two concentrations.

01:51 For our concentration of calcium, we know that we have 0 .050 molar calcium chloride, which will dissociate completely to yield 0 .050 molar calcium ion.

02:19 So there's our concentration for the calcium ion.

02:27 For our hydroxide ion, we know that our ph is 8 .0, so 14 minus 8 .0.

02:37 Equals 6 .0 and 10 to the negative 6 .0 equals a concentration of oh h.

02:49 I better write this down.

02:53 Equals 10 to the minus 6 .0 equals 1 times 10 to the minus 6th.

03:01 Malarity.

03:04 Our ion product constant will be 0 .0 .0 .0 molar.

03:13 And this is my calcium high.

03:15 Hydroxide and we're going to multiply that by 1 times 10 to the minus 6 molar squared, which is going to give me 5 times 10 to the minus 14th.

03:44 Q equals 5 times 10 to the minus 14th.

03:50 My ksp is 6 .5 times 10 to the minus 16th.

04:01 Q is less than my ksp, so we will have no precipitation.

04:10 The answer is no, it will not precipitate.

04:14 Q is less than ksp.

04:20 For the second part of this problem, we're asked if silver sulfate will precipitate when 100 milliliters of 0 .050 molar silver nitrate is mixed with 10 milliliters of 0 .0 .5.

05:05 5 .0 times 10 to the minus 2 molar sodium sulfate.

05:20 In order to figure this out, we are going to change both of our, we're going to change volume 2 liters.

05:39 So i'm going to take for my first part, let me highlight my first part here.

05:46 I'm going to use this information first.

05:53 Let's switch colors here.

05:58 I have 0 .110 .0 .0 .000.

06:02 Liters times 0 .050 moles per liter, which equals 5 .0 times 10 to the minus 3 moles...