Chemistry: Solubility Concepts

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Questions and Answers

What term describes the process when a solute's particles separate from the solution?

Crystallisation (correct)

Dissolution

Saturation

Solvation

Which statement correctly describes a saturated solution?

It is unstable and will always precipitate.

It loses solute particles to the environment.

It has reached a point where no more solute can dissolve. (correct)

It contains less solute than can be dissolved.

What key factor influences whether a solid solute will dissolve in a liquid solvent?

The polarity of both solute and solvent. (correct)

The pressure applied.

Only temperature.

The color of the solute.

Which of the following combinations correctly follows the 'like dissolves like' principle?

Sugar in water. Signup and view all the answers

What happens at equilibrium in a saturated solution?

Dissolution and crystallisation occur at equal rates. Signup and view all the answers

How does temperature generally affect the solubility of solid solutes in liquids?

Higher temperatures generally increase solubility. Signup and view all the answers

What characterizes an unsaturated solution?

It can still dissolve more solute at the same temperature. Signup and view all the answers

What defines solubility in a given solvent?

The maximum amount that can dissolve at specific conditions. Signup and view all the answers

What happens to the solubility of an endothermic dissolution process as temperature increases?

Solubility increases Signup and view all the answers

Which of the following accurately describes an ideal solution?

Has zero enthalpy and volume of mixing Signup and view all the answers

What characterizes a solution exhibiting positive deviation from Raoult's law?

Higher vapor pressure than predicted Signup and view all the answers

Which of the following is an example of a binary mixture that exhibits a negative deviation from Raoult's law?

Phenol and aniline Signup and view all the answers

What is a characteristic property of non-ideal solutions?

Vapor pressure deviates from Raoult's law Signup and view all the answers

In the formation of an azeotrope, what occurs at the azeotropic composition?

Liquid and vapor phases have the same composition Signup and view all the answers

What type of azeotrope results from a solution showing a significant positive deviation from Raoult’s law?

Minimum boiling azeotrope Signup and view all the answers

Which of the following factors does NOT significantly affect the solubility of solids in liquids?

Pressure changes Signup and view all the answers

Increasing the boiling point of a solvent when a non-volatile solute is added is known as:

Elevation of boiling point Signup and view all the answers

What effect does adding a non-volatile solute have on the vapor pressure of a solution?

Reduces vapor pressure Signup and view all the answers

What kind of interactions lead to negative deviations from Raoult’s law?

Stronger intermolecular forces among A-B than A-A and B-B Signup and view all the answers

Which of the following is true regarding the relation of pressure and solubility of liquids?

Solubility of gases increases significantly with pressure Signup and view all the answers

Which of the following properties is NOT affected by the addition of a non-volatile solute to a volatile solvent?

Molecular weight of solute Signup and view all the answers

What are colligative properties dependent on?

The total number of particles in the solution Signup and view all the answers

In which type of solution does no osmosis occur when separated by a semipermeable membrane?

Isotonic solution Signup and view all the answers

What is the effect of placing blood cells in a hypertonic solution?

Cells shrink and water flows out Signup and view all the answers

What happens to bacteria on salted meat due to osmosis?

They lose water, shrivel, and die Signup and view all the answers

What effect does a higher concentration of sodium chloride have on blood cells?

Stops water from entering the cells Signup and view all the answers

What type of solution has a salt concentration less than 0.9% (mass/volume)?

Hypotonic solution Signup and view all the answers

When one mole of KCl is dissolved in water, how many moles of particles are expected in the solution?

Two moles Signup and view all the answers

Why would the experimentally determined molar mass of an ionic compound be lower than the true value?

Because of the degree of dissociation Signup and view all the answers

What is an abnormal molar mass in the context of association of molecules?

Both A and B are correct Signup and view all the answers

What does Henry's law explain regarding the solubility of gases?

It increases with high pressure Signup and view all the answers

What medical condition can arise for scuba divers due to dissolved gases when ascending?

Decompression sickness (bends) Signup and view all the answers

How does temperature affect the solubility of gases in liquids?

Decreases with temperature rise Signup and view all the answers

What is one consequence of placing high concentration gas mixtures in scuba tanks?

Prevents nitrogen narcosis Signup and view all the answers

What process can be partly attributed to osmosis in plants?

Water movement from soil into roots Signup and view all the answers

Study Notes

Solubility of Substances

Solubility is the maximum amount of solute that dissolves in a given amount of solvent at a specific temperature and pressure.
Solubility depends on the nature of both the solute and solvent. Polar solutes dissolve in polar solvents, and nonpolar solutes dissolve in nonpolar solvents ("like dissolves like").
Dissolution is the process where a solute dissolves in a solvent.
Crystallization is the process where solute particles separate from the solution.
A saturated solution contains the maximum amount of solute dissolved at a given temperature and pressure.
Unsaturated solutions can dissolve more solute at the same temperature.

Temperature Effects on Solubility

The solubility of a solid in a liquid is significantly affected by temperature.
If the dissolution process is endothermic (ΔH_sol > 0), solubility increases with temperature.
If the dissolution process is exothermic (ΔH_sol < 0), solubility decreases with temperature.
These trends are observed experimentally.

Pressure Effects on Solubility

Pressure has a negligible effect on the solubility of solids in liquids because they are practically incompressible.

Ideal Solutions

Ideal solutions obey Raoult's Law at all concentrations.
Enthalpy of mixing (Δ_mixH) and volume of mixing (Δ_mixV) are both zero for ideal solutions.
In ideal solutions, intermolecular attractive forces between A-A, B-B, and A-B are similar.
Examples include n-hexane and n-heptane, bromoethane and chloroethane, benzene and toluene.

Non-Ideal Solutions

Non-ideal solutions do not obey Raoult's Law throughout all concentrations.
Solutions can show positive or negative deviations from Raoult's Law.
Positive deviations occur when A-B interactions are weaker than A-A or B-B interactions (e.g., ethanol and acetone). Vapor pressure is higher than predicted by Raoult's Law.
Negative deviations occur when A-B interactions are stronger than A-A or B-B interactions (e.g., phenol and aniline). Vapor pressure is lower than predicted by Raoult's Law.

Azeotropes

Azeotropes are binary mixtures with identical compositions in liquid and vapor phases.
They boil at constant temperatures and cannot be separated by fractional distillation.
Minimum boiling azeotropes form when solutions show large positive deviations from Raoult's Law.
Maximum boiling azeotropes form when solutions show large negative deviations from Raoult's Law.

Colligative Properties

Colligative properties depend on the** number** of solute particles, not their nature.
Examples include: relative lowering of vapor pressure, depression of freezing point, elevation of boiling point, and osmotic pressure.
These properties are useful in understanding phenomena like pickling food or water movement in plants.

Osmosis and Isotonic Solutions

Isotonic solutions have the same osmotic pressure at a given temperature.
No osmosis occurs between such solutions separated by a semipermeable membrane.
Normal saline (0.9% sodium chloride) is isotonic with blood.
Hypertonic solutions have a higher solute concentration than isotonic ones, causing water to flow out of cells.
Hypotonic solutions have a lower solute concentration, and water flows into cells, causing swelling.

Ionic Compounds and Molar Mass

Ionic compounds dissociate into ions when dissolved in water; this affects experimentally determined molar mass.
Abnormal molar mass occurs when molecules associate or dissociate in solution. This affects colligative properties.

Henry's Law and Applications

Henry's law describes the solubility of gases in liquids.
Increased pressure increases gas solubility.
Scuba diving (bends) and high-altitude effects are examples related to Henry's Law.
Soft drinks (increased CO2 solubility due to pressure) is also an example.

Effect of Temperature on Gas Solubility

Gas solubility decreases with increasing temperature.
Gas dissolution is an exothermic process, meaning heat is evolved during dissolution; hence, solubility decreases with increasing temperature.

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Description

This quiz explores the principles of solubility, including how temperature affects the solubility of substances. Learn about saturated and unsaturated solutions, and the relationship between polar and nonpolar solutes and solvents. Test your understanding of these critical chemistry concepts.