Properties of Water

Life depends on

Water

Water molecule is a

Polar Molecule

Polar molecule

Overall charge is unevenly distributed

_____ water molecules are created through polar covalent bonds

Individual

Due to its polarity, ___ water molecules are bonded together by hydrogen bonds

Multiple

Water molecules are bonded by

Hydrogen bonds

Hydrophilic

A polar molecule that interacts readily with or dissolves in water

Hydrophobic

A nonpolar molecule (fat, oil) that does not interact well with water

Heat

A measure of the total quantity of kinetic energy due to molecular motion in a body of matter

Temperature

Intensity of heat due to the average kinetic energy of the molecules

Calorie

The unit measure of heat

Liquid

Water molecules are constantly forming and breaking hydrogen bonds as water molecules move past each other

Liquid movement

Generates kinetic energy and causes bonds to break

Hydrogen bonds completely break and water molecules escape into the air as __

Gas

Decreased temperature

Not enough kinetic energy to break hydrogen bonds

Solid is less dense than

Liquid

Water molecules freeze, expand, and form a crystalline structure (___) maintained by hydrogen bonds

Solid

Important properties of water (4)

High heat capacity

High heat of vaporization

Solvent

Cohesion and adhesion

High heat capacity

Caused by hydrogen bonding

Specific heat

The amount of heat one gram of a substance must absorb or lose to change its temperature by one degree Celsius

4.186 Joules per gram per degree Celsius( J/g°C)

Water’s specific heat capacity

Equal to one calorie

4.186 Joules per gram per degree Celsius( J/g°C)

Heat of vaporization

The amount of energy required to change one gram of a liquid substance to a gas

Evaporation

Conversion of liquid to gas; fro water, it occurs on the water’s surface

Water acts as a heat sink or reservoir

Because it takes a lot of heat energy to bond hydrogen in liquid and prevent from breaking

Evaporative cooling

Energy is taken up during evaporation, cooling the surround environment.

Solvent

A substance capable of dissolving other polar molecules and ionic compounds

Solute

Any component dissolved in a solvent (hydrophilic)

Solution

A homogenous mixture of one or more solutes dissolved in a solvent

Sphere of hydration

Charges that surround the particle with water molecules

Order of S’s

Solvent→Solute→Solution

Dissociation

Occurs when atoms or groups break off from moles and form ions

Cohesion

Water molecules are attracted to each other, keeping the molecules together at the liquid-gas interface

Why is cohesion important for living organisms?

Habitat and chemical property

Surface tension

The capacity of a substance to withstand rupturing when placed under tension or stress

Responsible for the shape of water droplets

Surface tension

Adhesion

The attraction between water molecules and other molecules

Battle of the water

Adhesive force > Cohesive force

Capillary action

Water molecules are more attracted to charged glass tube and “climb” up the tube

pH

Indicates the acidity or basicity of a solution

pH tests measure the concentration of _______ ___ in a solution

Hydrogen ions

Acid

Substances that increase the H⁺ concentration of a solution

High concentration of H⁺ =high acidity=

low pH

Base

Substances that reduce the H⁺ concentration of a solution

Low concentration of H⁺ = low acidity=

high pH

pH scale

Ranges from 0-14

Anything > 8 is

Basic

pH of 7 is

Neutral

Anything <7 is

Acidic

Buffers

Substances that minimize charges in concentrations of H⁺ and OH^- in solutions

Buffers readily absorb excess H⁺ and OH^- ions, keeping the solution at a _______

Near-neutral pH

H

Hydrogen

OH

Hydroxyl group

Important Properties of Water Mnemonic Device

Happy Hippos Sing Classical (anthems)