Chemistry Solutions and Concentration

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Questions and Answers

What is the primary purpose of osmosis?

To dilute a concentrated solution

To allow solvent molecules to pass through a membrane (correct)

To remove solute molecules from the solution

To increase the temperature of the solvent

Which equation correctly represents osmotic pressure?

$ au = M/R$

$ ho = MRT$

$ u = MRT$ (correct)

$eta = MRT$

What characteristic distinguishes a colloid from a true solution?

Colloids can pass through a semipermeable membrane.

Colloids cannot disperse in a medium.

Colloids are always homogeneous.

Colloids consist of larger particles than solute molecules. (correct)

Which type of colloid is whipped cream categorized as?

Foam Signup and view all the answers

How do surfactants stabilize hydrophobic colloids?

By adsorbing to the surface and providing a layer of hydration Signup and view all the answers

What is the role of the hydrophobic tail in soap?

To dissolve grease and non-polar substances Signup and view all the answers

Which of the following best describes the Tyndall effect?

The scattering of light in a colloid Signup and view all the answers

What type of colloid is mayonnaise?

Emulsion Signup and view all the answers

What is the primary difference between a saturated solution and an unsaturated solution?

A saturated solution contains the maximum amount of solute, while an unsaturated solution contains less solute. Signup and view all the answers

Which statement accurately describes the interaction involved when a solute dissolves in a solvent?

Solvent-solute interactions are essential for the solution process. Signup and view all the answers

What is the formula for calculating percent by mass in a solution?

% by mass = mass of solute / (mass of solute + mass of solvent) x 100% Signup and view all the answers

Which type of solution contains more solute than what is present in a saturated solution?

Supersaturated solution Signup and view all the answers

What type of solute is more likely to dissolve in polar solvents?

Soluble ionic compounds. Signup and view all the answers

What is the molarity of a solution prepared by dissolving 5 moles of solute in 2 liters of solution?

2.5 M Signup and view all the answers

Which of the following statements regarding dilution is true?

The moles of solute remain constant before and after dilution. Signup and view all the answers

Which example represents a solid in a solid solution?

Brass alloy Signup and view all the answers

Study Notes

Solutions and their Types

A solution is a homogeneous mixture of two or more substances.
The substance present in the smaller amount is called the solute, and the substance present in the larger amount is called the solvent.
Solutions can be classified based on the state of the solute and solvent.
Examples of solutions include air (gas in gas), soda water (gas in liquid), brass (solid in solid), and salt water (solid in liquid).

Solution Concentration

A saturated solution contains the maximum amount of solute that a solvent can dissolve at a specific temperature.
An unsaturated solution contains less solute than the solvent can dissolve at a specific temperature.
A supersaturated solution contains more solute than is present in a saturated solution at a specific temperature.

Interactions in Solutions

Three types of interactions are involved in the solution process: solvent-solvent interaction, solute-solute interaction, and solvent-solute interaction.
The rule "like dissolves like" applies to solubility.
Non-polar molecules are soluble in non-polar solvents (e.g., CCl₄ in C₆H₆), while polar molecules are soluble in polar solvents (e.g., ethanol (C₂H₅OH) in H₂O).
Ionic compounds are more soluble in polar solvents (e.g., NaCl in H₂O or NH₃).

Concentration Units

Concentration is the amount of solute in a given quantity of solvent or solution.
Common concentration units include:
- Percent by mass: (mass of solute / mass of solution) x 100%
- Mole fraction (X): moles of A / sum of moles of all components
- Molarity (M): moles of solute / liters of solution
- Molality (m): moles of solute / mass of solvent (kg)

Dilution

Dilution involves preparing a less concentrated solution from a more concentrated solution.
The moles of solute before dilution (i) equals the moles of solute after dilution (f): M_iV_i = M_fV_f

Osmosis and Osmotic Pressure

Osmosis is the movement of solvent molecules through a semipermeable membrane from a dilute solution to a more concentrated one.
A semipermeable membrane allows passage of solvent molecules but blocks passage of solute molecules.
Osmotic pressure (π) is the pressure required to stop osmosis.
Osmotic pressure is calculated using the formula π = MRT, where M is molarity, R is the gas constant, and T is temperature (in Kelvin).

Colloids

A colloid is a dispersion of particles of one substance throughout a dispersing medium of another substance.
Colloidal particles are much larger than solute molecules, and colloidal suspensions are not as homogeneous as solutions.
Colloids exhibit the Tyndall effect, which is the scattering of light as it passes through the colloid.
Colloids can be classified based on the dispersing medium and dispersed phase.
Examples of colloids include fog (liquid in gas), smoke (solid in gas), mayonnaise (liquid in liquid), milk of magnesia (solid in liquid), and jelly (solid in liquid).
Hydrophilic colloids are water-loving, while hydrophobic colloids are water-fearing.

Hydrophobic Colloid Stabilization

Hydrophobic colloids can be stabilized using surfactants.
Surfactants have both hydrophilic and hydrophobic ends.
The hydrophobic ends adsorb to the surface of the hydrophobic colloid, and the hydrophilic ends extend into the surrounding water, preventing aggregation.

Cleansing Action of Soap

Soap acts as a surfactant, with a hydrophilic "head" and a hydrophobic "tail".
The hydrophobic tail dissolves grease and gets attracted to it.
The hydrophilic head is attracted to water.
This forms a micelle, trapping the grease molecules inside and allowing them to be washed away by water.

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Description

Explore the different types of solutions, their classifications, and the concepts of solution concentration. This quiz will help you understand the interactions between solutes and solvents and how these influence the properties of solutions. Test your knowledge on saturated, unsaturated, and supersaturated solutions.