2.2 Water and Life

water is the biological medium on earth

cells are surrounded by and composed of (70-95%) water
Very essential to life

Water is a polar molecule

oxygen is more electromagtivity, this make a slight negative at oxygen and slight positive at hydrogen. This results in hydrogen bonds.

Positive and Negative forces attract.

Water is not a good lubricant,sticky

Non polar molecules don't stick, polar molecules stick.

kinetic energy: energy of motion

Energy: the ability to do work

heat: measure of the total amount of kinetic energy or transfer energy.

More kinetic energy the more heat

high=hot lower=cool

temperature: measures the intensity of heat due to the average kinetic energy of molecules.
water has a dense heat capacity
Temperature is the measure of air particles moving.
Every particle has kinetic energy
==water== moves, as the kinetic energy increases the hydrogen bonds in water molecules break apart.
Water Is harder to move kinetic because of hydrogen bonds, takes more energy.

Unique Properties Of Water

$Solid water floats on liquid- solid water is lighter than liquid water. Ice floats. If water sank it would be dangerous. Ice insulates like a blanket so it stays warm underneath$
$high heat capacity and heat of vaporization$
$Versatility as a solvent to dissolve polar molecules$
$Cohesion and adhesive- sticky /co-water sticks together. Ad- water sticking to something else. Capiliary action- the climbing of water up a surface. ( Trees going up roots)$
$Dissociating into ions$
$Water reaches$ $it’s greatest density at 4 celcius$
$when frozen it becomes less dense$

Water Moderates Temperature

==Specific Heat: is the amount of energy one gram of a substance must absorb or lose charge its temperture by one degree Celsius==.
==Calorie is the amount of heat required to raise the temperature of 1g of water by 1 degree celsius- water is resistant to heat , keeps 🌍 cold==
Water takes a while to heat and cool
water can absorb or release a large amount of heat with only a slight change in it’s own temperature. Can absorb without getting hotter itself.
Water absorbs heat from warmer air and releases stored heat.
Difficult to separate water into a gas because of hydrogen bonds.
When water cools/freezes it is releasing heat.
hydrogen bonds break= heat absorbed
Hydrogen Bonds form=heat released
evaporation= cooling process
Water keeps everything in a moderate range keeps Earth balanced
evaporative cooling= the remaining surface cools

  ## Water As A Solvent
  * Solution=homogeneous mixture of substances, mix things water
  * solvent=dissolving agent of a solution
  * solute=substance that is dissolved
  * Water is polar and will dissolve other polar molecules and ions
  * hydrophilic=substance has an affinity for water/ loves water hydro=water philic=loving
  * @@hydrophobic=substance does not have an@@ affinity for water/dosen’t like water , oil, greases, wax-non polar hydro=water phobic=fearing
  * Water is a versatile solvent due to polarity

^^Polar (H20) can mix with polar and ionic^^
Water is versatile solvent due to its polarity

Acids And Bases

The hydrogen bond between two water molecules can shift from one another
Concentrations of H+ and OH- are equal in pure water.
Biologists use the pH scale to describe whether a solution is a acidic or basic.
Any acid( dissolve materials) is any substance that increases the H+ concentration of a solution.
A base( dissolve materials) is any substances that removes protons from a concentration of a solution.
Buffer: stops pH change, resist change, works in both direction.