Unit 1 Notes 2: Properties of Water

Water is a _____ molecule

polar (opposite ends have opposite charges)

Polarity allows water molecules to form ________ _____ with each other.

hydrogen bonds

Properties of water

cohesion, adhesion, excellent solvent, solid is less dense than liquid, specific heat

Cohesion

hydrogen bonds allow water molecules to bond to other water molecules

Adhesion

attraction between water and different substances

cohesion and adhesion allow for _____

capillary action

Capillary Action

tendency of water to rise in a thin tube (plants)

Adhesion causes H2O to Hydrogen bond with ____

Plant xylem

Cohesion allows H2O to Hydrogen bond with ____

Other H2O molecules

Hydrogen bonding between water molecules (Cohesion) causes:

Surface Tension

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid

Water absorbs heat from ____ and releases stored heat to ____

warmer air, cooler air

specific heat

The amount of energy required to raise the temperature of 1 gram of a substance by 1 degree celcius

When water absorbs heat, hydrogen bonds are ____ and water can move freely

broken

When the temperature of water decreases, the hydrogen bonds are ____ and ____ a considerable amount of energy

formed, release

specific heat of water

4.184 J/gC

The high specific heat of water ____ temperature fluctuations to within limits that permit of life

minimizes

The high specific heat of water also allows the body to ____ heat very slowly to retain body temperature

lose

heat of vaporization

the energy a substance must absorb in order to change from a liquid to a gas

evaporative cooling

As a liquid evaporates, its remaining surface cools

Solvents

dissolve solutes into an aqueous solution

When an ionic compound dissolves in water:

each ion is surrounded by a sphere of water molecules called a hydration shell

Hydrophilic substances

have an affinity for water

Hydrophobic substances

do not have an affinity for water

Amphipathic molecules

have both hydrophilic and hydrophobic properties (phospholipids)

Amphipathic interactions in a phospholipid:

The hydrophilic heads of the phospholipid bilayer interacts with water (Hydrogen bonding) both outside and inside of the cell and the hydrophobic tails interact with each other in the middle of the bilayer (Hydrophobic interactions)

Concentrations of H+ and OH- are ____ in pure water

equal

Organism are ____ to pH changes

sensitive

acidic solution

A solution that has a pH below 7.0 (neutral)

basic solution

A solution with a pH greater than 7.

Most biological fluids have pH values in the range of

6-8

internal pH of most living cells...

must remain close to pH 7

Buffers

substances that minimize changes in pH

medulla (lower brain)

continuously monitors blood pH

When blood pH drops...

the medulla will stimulate the diaphragm and rib muscles to contract so you can take in more O2 and release more CO2. This process is an example of negative feedback and operates to maintain homeostasis

acid precipitation...

is caused mainly by the mixing of different air pollutants with water in the atmosphere and can fall at some distance from the source of pollutants

greenhouse effect

Natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases

acidification of oceans

Leads to a decrease in the ability of corals to form calcified reefs. (Coral bleaching)