Lecture 2: properties of water

water is what fraction of earths surface

___3/4______ of the Earth’s surface is submerged in water

  Cells are composed of

70 to 95% of water

Unequal sharing of water makes it a

•       polar molecule  (charged)

between neighboring molecules with interactions are happing

hydrogen bonds

Properties of Hydrogen Bonds:

 

1.     Weak (compared to ionic or covalent bonds)

 

2.     Water molecules must be very close for the weak attraction to be effective

 

3.     Are only able to exist when water is in the liquid or solid phase. 

-Cannot exist when water is in the gas phase

4.     Most stable when water is in the solid phase

5. When water is in the liquid state, the hotter the temperature, the less stable to bonds become.

Water’s Life Supporting Properties: (5 properties)

1.     High heat capacity (moderates temperature)

2.     High heat of vaporization (moderates temperature)

3.     Solvent of life

4.     Cohesive nature

5.     Ice floats

 

High heat capacity  

–      Can absorb a lot of heat without increasing in temperature

–      Important in maintain a constant body temperature 

high heat of vaporization

• removes heat from the earths surface

• as water vaporates takes heat with it

• good cooling mechnism

solvent of life

• water dissolves polar molecules

• transporting biological molecules in your body

solvent and solute example

water is solvent and dissolved substance is the solute (salt)

Hydrophillic

water soluble likes water - polar molecules

hydrophobic

does not dissolve in water, nonpolar moleculesn

amphiphillic

molecules that is both hydrophillic and phobic

how does soap work

soap molecules arrange themeselves around fat particles called micelles

water has a cohesive nature

attraction of water molecules to other water molecules

• cohesion is vital for water transport in plants

• high surface tension

cohesion

water molecules cling to each other through hydrogen bonds

adhesion

water molecules cling to the surfaces

ice floats bc

at low temps, hydrogen bonds don’t break

when water molecules get cold they Move apart

As liquid water cools it becomes

LESS DENSE, it expands as it freezes therefore floats