High School Chemistry : Help with Solubility Rules

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #1 : Solutions And Mixtures

Which of the following will lead to an increase in solubility of sodium chloride in water?

Possible Answers:

Decreasing pressure and temperature of the solution

Lowering the temperature of the solution

Increasing in temperature of the solution

Decreasing the pressure of the solution

Adding other solutes with the same chemical properties

Correct answer:

Increasing in temperature of the solution

Explanation:

Solubility of solid and liquid solutes in aqueous solutions can be increased by raising the temperature of the solution. Raising the temperature increases the amount of kinetic energy of the water molecules, allowing them to better interact with the solute particles and prevent the formation of a solid lattice.

Adding other solutes with similar properties will generally decrease solubility by the common ion effect, or else will not affect solubility at all. Increasing pressure will help increase the solubility of a gas in solution, but will not affect solutions that only contain solids and liquids. Note that gas solubility will also increase with decreased temperature. This is opposite to the relationship between temperature and the solubility of solids. Low temperature will reduce the kinetic energy of gases, making them more similar to liquids, while lowering the temperature of a solid will further lower its kinetic energy and decrease its similarities with a liquid solvent.

Example Question #2 : Solutions And Mixtures

Silver chloride is an insoluble salt when in solution. Which of the following salts will decrease the solubility of silver chloride if added to the solution?

Possible Answers:

Sodium bromide

Magnesium fluoride

Calcium bromide

Sodium chloride

Correct answer:

Sodium chloride

Explanation:

It is possible to reduce the solubility by adding a salt that increases the concentration of an ion that is created by the insoluble salt. This is called the common ion effect.

Silver chloride will dissociate into silver and chlorine ions in solution.

If sodium chloride is added to the solution, the concentration of chlorine ions increases.

This will push the equilibrium of the silver chloride dissociation to the left, thus decreasing the solubility of silver chloride.

Example Question #3 : Solutions And Mixtures

Which of the following salts is insoluble?

Possible Answers:

Correct answer:

Explanation:

There are some general solubility guidelines that can help you predict which salts are soluble.

1. All compounds containing ammonium, nitrate, or alkali metals are soluble.

2. Compounds with halogens as the anion are soluble. The three noted exceptions are when they are bonded to silver, mercury, or lead.

3. Sulfate compounds are soluble, except when bonded to mercury, lead, or the heavier alkaline earth metals.

 is an example of an insoluble sulfate compound because the sulfate is attached to barium, a heavy alkaline earth metal.

Example Question #1 : Solutions And Mixtures

How does the temperature of a solvent affect the solubility of a solid? How does temperature of a solvent affect the solubility of a gas?

Possible Answers:

As the temperature of the solvent increases, solubility of solids increases. As the temperature of the solvent increases, solubility of gasses increases

The temperature of a solvent does not change the solubility of solids or gasses

As the temperature of the solvent increases, solubility of solids decreases. As the temperature of the solvent increases, solubility of gasses decreases

As the temperature of the solvent increases, solubility of solids decreases. As the temperature of the solvent increases, solubility of gasses increases

As the temperature of the solvent increases, solubility of solids increases. As the temperature of the solvent increases, solubility of gasses decreases

Correct answer:

As the temperature of the solvent increases, solubility of solids increases. As the temperature of the solvent increases, solubility of gasses decreases

Explanation:

Solubility of solids increases when temperature increases because the increased kinetic energy increases the chance that a solute molecule gets surrounded by solvent molecules. Solubility for gases decreases when temperature increases because the increased kinetic energy allows for the gas molecules to break the intermolecular forces holding them in the solution, letting them bubble out of the solvent.

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