Chapter 15 Aqueous systems

What are the results of hydrogen bonding?

water's high surface tension, low vapor pressure, and high boiling point

Surface tension:

the inward force that ends to minimize the surface era of a liquid

A \_______ can decrease the surface tension of water

surfactant

Surfactant:

any substance that interferes with the hydrogen bonding between water molecules and thereby reduces surface tension

Give 2 examples of surfactants

soaps and detergents

Vapor Pressure:

the result of molecules escaping from the surface of the liquid and entering the vapor phase

Describe molecular compounds of low molar mass

usually gases or liquids with low boiling points at normal atmospheric pressure

How does hydrogen bonding affect water's boiling point?

It takes more energy to break the ion attractions between water molecules. If the hydrogen bonding in water was weak it would be a gas at the usual temperatures.

Heterogeneous mixture:

components that make up the mixture are not evenly distributed

Heterogeneous mixtures can be classified as:

suspension or colloid

Suspension:

particles in a mixtures will settle and can be seen (sand in water)

Colloid:

between a true solution and a suspension, particles do not settle, particles scatter light in a transparent medium (Tyndall effect), random movement of particles (Brownian movement)

Tyndall effect:

when colloidal particles scatter light in a transparent medium

Brownian movement:

the observed random motion of microscopic particles suspended in a fluid, caused by collision with molecules of the surrounding medium

Emulsion:

a type of colloidal system where there is colloidal dispersion of a liquid in a liquid

Homogeneous mixture:

a solution, the components that make up a mixture are distributed evenly, same composition and properties throughout

Solution:

a homogeneous mixture of 2 or more substances in a single physical state

List the types of solutions

solid, liquid, gas, and aqueous

When describing a type of solution identify the \________ first and the \______ last

solute, solvent

Solute:

part of the solution that is dissolved (less of it)

Solvent:

part of the solution that does the dissolving (usually more of)

Dissolving:

when solute particles fit between solvent particles (complete mixing)

Melting:

when a solid is heated enough so that the particles can slide past on another

Solvation:

the interaction between solute and solvent

Hydration:

when water is the solvent

Solubility:

the amount of a substance that dissolves in a given quantity of solvent at a certain temperature to form a saturated solution

What types of substances dissolve most readily in water?

ionic and polar covalent compound

Wh at type of substances does not easily dissolve in water?

nonpolar covalent compounds (methane-\>oil, grease, gasoline)

What happens when ionic compounds dissolve in water?

they dissociate completely and form ions (dissociation)

What happens as a result of dissociation:

the solution becomes an electrolyte (it conducts electricity)

Ionic compounds conduct electricity only in the \_______ and \______ phase.

Molten, aqueous (because ions are free to move)

Ionization:

When molecular compounds, usually polar molecules, are mixed with water, the weak covalent bonds of the solute are overcome by the strong polarity of the solvent, water, and produce ions