Chemistry Ch. 15-16

Define the terms solute, solvent, and aqueous solution. Provide an example of each.

A solute is the dissolved particles in a solution. Sodium chloride is a solute. A solvent is the dissolving medium. Water is a solvent. An aqueous solution is water that contains dissolved particles. Salt-water is an aqueous solution.

Emulsion

Colloid of a liquid in a liquid

Dispersed phase

Colloidal particles spread throughout a suspension

Weak electrolyte

Compound that ionizes incompletely in aqueous solution

Electrolyte

Compound that will conduct current in the liquid state or in aqueous solution

Immiscible

Describes liquids that are insoluble with one another

Solute

Dissolved particle

Solvent

Dissolving medium

Tyndall effect

Phenomenon observed when beam of light passes through a colloid

Describe the process of solvation.

Solvation is the process in which the positive and negative ions of an ionic solid become surrounded by solvent molecules.

Discuss the phenomenon of supersaturation. Indicate how crystallization can be initiated in a supersaturated solution.

Supersaturated solutions contain more solute than it can theoretically hold. Crystallization occurs when there is agitation or a seed crystal is added.

Discuss the factors that can affect the solubility of a substance. Include specific examples in your discussion.

Temperature and pressure affect solubility. An increase in temperature in a sodium chloride solution is small- from 36.2g in 100g of water at 25 degrees Celsius to 39.2g in 100g of water at 100 degrees Celsius. Pressure affects gases the most; bottled drinks are an example.

Explain what a saturated solution is. Give a specific example.

A saturated solution contains the max amount of solute for a given quantity of solvent at a constant temperature and pressure. At 25 degrees Celsius, 36.2g of sodium chloride in 100g of water forms a saturated solution.

What does a surfactant do? Include an example of a surfactant in your discussion.

A surfactant interferes with the hydrogen bonding between water molecules and therefore reduces surface tension. Soaps are surfactants.

Distinguish among a suspension, colloid, and solution. Give an example of each.

A suspension has larger particles than a solution and suspension. Clay mixed with water is a suspension. A colloid has larger particles than a solution. Milk is a colloid and salt water is a solution.

What is an electrolyte? Give examples and distinguish between a strong electrolyte and a weak electrolyte.

An electrolyte is a compound that conducts an electrical current when it is in an aqueous solution or the molten state. Sodium chloride and copper (II) sulfate are electrolytes. In a strong electrolyte solution, all or nearly all of the solute are ions, and in a weak electrolyte solution only a fraction of the solute are ions.

What is the shape of a water molecule?

Bent

Aqueous solution

Homogeneous mixture of water and dissolved substances

What causes water's low vapor pressure?

Hydrogen bonding

The bonds between adjacent water molecules are called?

Hydrogen bonds

Why is ice less dense than water?

In liquid water, the molecules are packed closer together than ice.

Surface tension

Inward force tending to minimize surface area of a liquid

Explain on a particle basis how the addition of a solute affects the boiling point, freezing point, and the vapor pressure of the solvent.

It increases the boiling point because it will take a higher temp to boil the added substance. It lowers the freezing point because it will take a colder temp to freeze the added substance. It decreases the vapor pressure.

How does the surface tension of water compare with the surface tensions of most other liquids?

It is higher

Concentration

Measure of the amount of solute dissolved in a specified quantity of solvent

Colloid

Mixture in which particle size averages between 1nm and 1000 nm

Suspension

Mixture in which particle size averages greater than 1000 nm in diameter

Compare and contrast molarity and molality.

Molarity is the number of moles of solute dissolved in 1L of solution, while molarity is the number of moles of solute dissolved in 1kg of solvent.

Saturated solution

Solution containing max amount of solute

Describe the structure of the water molecule and indicate how this structure is responsible for many of the water's unique properties.

The water molecule consists of three atoms. The oxygen atom forms covalent bonds with each hydrogen bond. The electronegativity difference causes the water molecule to be polar. The hydrogen bonds result in its high surface tension, low vapor pressure, and high boiling point.