Biochemistry 1 Properties of Water

A water molecule is composed of what atoms?

1 oxygen atom connected to 2 hydrogen atoms

What causes the water to be polar?

In each water molecule, the oxygen atom attracts more than its fair share of electron, therefore:

The oxygen acts partially negative
The hydrogen acts partially positive

Hydrogen bond between water molecules

• One hydrogen bond is weak but many is strong

• The negative oxygen attracts to a positive hydrogen of the other water molecule

What is the boiling point of water based on the altitude/elevation?

The higher the altitude/elevation the boiling point of water decreases due to the lower atmospheric pressure

At sea level, pure water boils at 100 Celcius and freezes at 0 Celcius

What are the 4 properties of water?

• Cohesion

• Adhesion

• Specific heat

• High heat of vaporization

Cohesion

It is the attractive force between the water molecules

Results in Surface Tension and creates Surface Film

Surface Tension

a measure of the strength of water’s surface. The tightness across the surface of water that is caused by the polar molecules pulling on one another.​

Surface Film

it allows insects to walk on the surface of water

Adhesion

it is when molecules of water are attracted to other substances. It allows water to stick with other things like plants, glass, soil, cotton, and etc.

Capillary Action

It is an action where both cohesion and adhesion allow water to move upwards.

Transpiration

process which plants and trees remove water from the soil, and paper towels soak up water.

Specific heat

is the amount of heat needed to increase the temperature of 1kg of substance by 1C, water requires a lot of specific heat, -4.184 J/kg per C