What characteristic of water makes it so important to life and allows for the 4 properties discussed in class?

water has a very high polarity which allows it to create the 4 emergent properties

What are the 4 emergent properties?

cohesion ,specific heat, expansions upon freezing, and solvent

What can polar molecules form?

hydrogen bonds

What is cohesion and why do they help life?

it is bonding between like molecules and help by leading to adhesion, hydrogen bonds, and surface tension

Adhesion

bonding between UNLIKE molecules

Cohesion and adhesion allow…

allow plants to overcome gravity and capillary action

What is capillary action?

climbing up something without the help of a force (paper towel cleaning up a spill)

Specific heat

for every 1g of heat absorbed or lost, the substance changes by 1-degree Celsius, the specific heat of water is very high and when head is absorbed to break H-bonds and when it is released it forms H-bonds

How does specific heat help life?

water monitors air temperature

Kinetic Energy

Kinetic energy is a property of a moving object or particle and depends not only on its motion but also on its mass

Thermal energy

random movement of atoms and molecules

Temperature example

average kinetic energy

Heat

thermal energy transfers (calories and joules

Water monitors…

air temperature

Stable ocean temperatures

37-72 degrees Fahrenheit in New London, CT

Ice

crystalline structure; 1 H2O binds 4 others

Density of water vs. ice. vs evaporated water

water is liquid, ice is solid, evaporated water is gas

Expansion upon freezing

ice insulates the water, doesn’t freeze solid, life lives under it

Solute + Solvent =

solution

Aqueous solution

any mixture where a substance is mixed into water

Hydrophilic

likes water

Hydrophobic

dislikes water

Water is…

polar with partial charges

Concentration

the amount of solute in a unit vol of solution (1g/L)

Solvent Importance

most chemical reactions involve molecules dissolved in water inside cells, outside cells

Amphipathic loves

molecules with BOTH hydrophilic and hydrophobic regions (detergents/soaps)

Micelles

the formation of spheres when amphipathic molecules aggregate in water (equal amounts of each in pure water)

What can water molecules dissociate into? (micelles)

hydroxide ions (OH-) and hydrogen ions (H+)

Acids

release H+

Strong acid

completely dissociates (hydrochloric acid HCL→ H+CL-)

Weak acid

some of the original molecule remains (Carbonic acid H2CO3 H+ + HCO3-)

Bases

absorb H+ (Sodium hydroxide NaOH → Na+ + OH- OH- + H+ H2O)

pH

pH: measure of the [H+] of a solution 
• pH = -log10 [H+] 
• Addition of acids & bases can change it 
• Acidic: more H+ 
• Alkaline: more OH- 

Since H+ and OH- can readily bind to many ions and 
molecules, pH can thus affect?

• The function of molecules 
• The rates of chemical reactions 
• The ability of ions or molecules to dissolve

The pH of living cells:  

• Shifts in pH can drastically alter the function & viability of cells 
• Ex. Exercise makes lactic acid; certain diseases can raise/lower 
blood pH 
• Both acids AND bases can cause chemical burns. 

Buffers

a pair of substances that minimize changes in 
pH of the fluids of living organisms 

Buffer examples

• A weak acid & a related base 
• Bicarbonate pathway 
• Carbonic acid (H2CO3) 
• Bicarbonate ions (HCO3-) 
• H2CO3 H+ + HCO3 

Solute

A substance that is dissolved in a solvent to form a solution. 
Example: Salt is the solute in salt water. 

Solvent

A substance, usually a liquid, that dissolves a solute to form a solution. 
Example: Water is the solvent in salt water.  

Solution

A homogeneous mixture in which one substance (the solute) is dissolved in another substance (the solvent). 
Example: Salt water is a solution.  

Aqueous

Relating to, containing, or dissolved in water. 
Example: An aqueous solution has water as its solvent.  

Concentration

The amount of a substance (solute) present in a given amount of solution. 

Amphipathic

Having both a hydrophilic (water-attracting) region and a hydrophobic (water-repelling) region. 
Example: Phospholipids are amphipathic.  

Micelles

Spherical structures formed when amphipathic molecules arrange themselves in water, with their hydrophobic parts facing inward and hydrophilic parts facing outward. 
Example: Soap molecules can form micelles around grease.  

Bilayer

A structure made of two layers of molecules, especially the two layers of phospholipids that make up a cell membrane. 
Example: The cell membrane is a phospholipid bilayer.