ilovepdf_merged NEEDYUMPU

The Learning Goal for this assignment is:
The students will learn how the interaction between water molecules account for the
unique properties of water and how aqueous solutions form
Page 124
Take note over the following chapter. Use the Headings provided to organize your notes. Define and number all highlighted vocabulary (total 22 ) as well
as summarize and take notes over the sections. You may add pictures where needed. The pictures should be an appropriate size. Use Arial 12 for all
text. This document should be 2 pages and should be saved as a pdf before you submit it into Angel.
Chapter 15 Water and Aqueous Systems
Pages 488 - 507
15.1 Water and Its Properties
Water in the Liquid State
Many unique and important properties of water – including its high surface tension, low vapor pressure,
and high boiling point – result from hydrogen bonding
Surface Tension - The inward force or pull that tends to minimize the surface area of a liquid. Surfactant –
Any substance that interferes with the hydrogen bonding between water molecules and thereby reduces
surface tension
Water is a simple molecule requiring three atoms; the oxygen atom forms a covalent bond with each of
the hydrogen atoms. In a water molecule, the bond polarities are equal, but the two poles do not cancel
each other because a water molecule is bent. The molecules as a whole is polar; the negative end
attracts the positive end. Hydrogen bonding also occurs – the oxygen atom has a partial negative charge.
The surface of water acts like a skin – the ability of water molecules to form hydrogen bonds with other
molecules that surround them on all sides. Water forms nearly spherical drops on a leaf. Water molecules
at the surface of the water drop cannot for hydrogen bonds with molecules in the air, so they are drawn
into the body of the liquid. Water drops bead up on some surfaces, is added to water, the drop spreads
out. So basically a surfactant causes the beads of water to collapse and spread out. An extensive network
of hydrogen bonds holds the molecules in liquid water to one another. These hydrogen bonds must be
broken before water changes states so the tendency of these molecules to escape is low and evaporation
is slow. Molecular compounds of low molar mass are usually gases or liquids with low boiling points at
normal atmospheric pressure.
Water in the Solid State
The structure of ice is a regular open framework of water molecules in a hexagonal arrangement
As a typical liquid cools, it begins to contract and its density increases gradually; it increases because the
molecules of the liquid move closer together so that a given volume of the liquid contains more molecules
and thus more mass. A typical solid sinks in its own liquid because the density of the solid is greater than
that of the corresponding liquid. As water begins to cool, it behaves initially like a typical liquid, it contracts
slightly and its density gradually increases. Below 4 ° C, water no longer behaves like a liquid and at 0° it
forms as ice. The unique properties of ice are a result of hydrogen bonding. Extensive hydrogen bonding
in ice holds the water molecules farther apart in a more ordered arrangement than in liquid water. The
hexagonal symmetry of a snowflakes reflects the structure of the ice crystal. A layer of ice acts like an
insulator acts.
15.2 Homogeneous Aqueous Systems
Solutions
Substances that dissolve most readily in water include ionic compounds and polar covalent compounds.
Aqueous solution: water that contains dissolved substances Solvent: In a solution, the dissolving medium
Solute: The dissolved particles in a solution. Salvation: The process by which the positive and negative
ions of an ionic solid become surrounded by solvent molecules
Water dissolves so many of the substances that in comes in contact with making it an aqueous solution. A
solvent dissolves the solute, and the solute becomes dispersed in the solvent. They can be any state of
matter. Solutions are homogeneous mixtures and stable mixtures. Nonpolar covalent compounds, such as