# Chemistry solubility and precipitate

• temari
You correctly calculated the mass of the precipitate and then used the solubility product constant to find the concentration of fluoride ions at the saturation point. From there, you were able to solve for the added concentration of KF and then convert it to the mass of KF. Overall, your summary is accurate and concise. Good job!
temari

## Homework Statement

A solution contains 1.73 x 10^-3 mol/L of Ba(NO3)2(aq) and 1.2 x 10^-3 moles of NaF. What mass of KF added to this solution would produce 2.7 x 10^-3g of precipitate from this solution if the Ksp of BaF2 is
1.84 x 10-7 and you have 1.0L of solution?

## The Attempt at a Solution

Mass of BaF2 = 2.7*10^-3g/ 175.3 (molar mass)
= 1.5*10^-5 moles/L

Ksp = (ba) (F)^2
1.84*10^-7 = (1.73 x 10^-3 - 1.5*10^-5) (Concentration of F)^2
(1.84*10^-7 /.001715)^.5 = (Concentration of F)
.0103 = (Concentration of F at Saturation Point)

2 x 10^-3 moles of NaF + (Added Concentration of KF) - 2(1.5*10^-5 moles/L) = .0103

(Added Concentration of KF) = .00833 mol/L
.00833 mol/L * (Molar Mass of KF 58.1) = .484 g of KF

Did I answer this Question Correctly

Last edited:
I have not checked the answer, but the approach looks OK.

## 1. What is solubility in chemistry?

Solubility in chemistry refers to the ability of a substance, known as the solute, to dissolve in another substance, known as the solvent. It is a measure of how much of a solute can dissolve in a given amount of solvent at a specific temperature and pressure.

## 2. How is solubility determined?

Solubility is determined by the chemical properties of the solute and solvent, as well as the temperature and pressure of the system. It is typically measured in units of mass per volume, such as grams per liter or moles per liter.

## 3. What is a precipitate in chemistry?

A precipitate in chemistry refers to a solid substance that forms when two solutions are mixed together and a chemical reaction occurs. It is the result of a reaction between the solute and solvent that produces an insoluble compound.

## 4. How is the solubility of a substance affected by temperature?

In general, the solubility of a substance increases with increasing temperature. This is because higher temperatures provide more energy for the solvent molecules to overcome the intermolecular forces holding the solute particles together, allowing them to dissolve more easily.

## 5. How can solubility be used to separate substances?

Solubility can be used as a separation technique by taking advantage of the different solubilities of substances in a mixture. By manipulating the temperature or adding different solvents, it is possible to dissolve one substance while leaving the other as a solid precipitate, allowing for the separation of the two substances.

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