Properties of Water Notes

Honors Biology

Water in Living Things

One Example of Homeostasis

Organisms remove excess

heat through water

evaporation, while also

maintaining heat with water.

This allows organisms to

maintain a constant internal

temperature which is one

example of maintaining

homeostasis.

Properties due to Water’s Polarity

1. Versatile solvent

2. Cohesion

Example: surface tension

3. Adhesion

Example: capillary action

4. Specific Heat/Heat Capacity

5. Heat of Vaporization

6. Freezing

Structure of the Water Molecule

The molecular formula for water is H2O.

It consists of 2 hydrogen atoms and 1 oxygen atom.

Covalent bonds connect hydrogen and oxygen.

Why is Water Polar?

Water is a polar molecule, meaning that there is an unequal distribution of electrons. Let’s look at electronegativity.

Oxygen is partially negative, and hydrogen is partially positive.

What is Hydrogen Bonding?

The hydrogen atom from one water molecule bonds

weakly to the oxygen atom of another water molecule

through a hydrogen bond.

Properties due to Water’s Polarity

1. Versatile solvent

2. Cohesion

Example: surface tension

3. Adhesion

Example: capillary action

4. Specific Heat/Heat Capacity

5. Heat of Vaporization

6. Freezing

What is the Versatile Solvent?

Polarity of the water molecule means that it can attract

other molecules that are charged or polar.

Water can also dissociate ionic bonds. NOTE: This is not

a chemical reaction.

Hydrophilic – molecules that are polar/have a charge

and; therefore, attracted to water

Hydrophobic – molecules that are nonpolar/don’t

possess a charge and; therefore, are not attracted to water

What is Cohesion?

Water is attracted to other water molecules

due to hydrogen bonding.

The oxygen end of water has a negative charge

The hydrogen end has a positive charge.

What is Adhesion?

Water is attracted to other substances that are

polar or have charges due to hydrogen

bonding.

Capillary action is limited by gravity

Specific Heat in Water

Review: What are the common states of matter and the transitions between them?

High Specific Heat/Heat Capacity - water temperature changes slowly and holds temperature well.

Why? Hydrogen bonds require an input of energy to break therefore requiring more energy for water to change states of matter than non-polar or non-charged molecules

Heat of Vaporization

High Heat of Vaporization - Water requires a lot of energy to vaporize. When organisms sweat or dogs pant, they release a high amount of heat energy.

Why? Hydrogen bonds require an input of energy to break therefore requiring more energy for water to change states of matter than non-polar or non-charged molecules

Density Changes

Water is less dense in solid form – Solid water molecules form a lattice that is less dense then liquid water and therefore floats.

Why? The partial positive hydrogens must face the partial negative oxygens of adjacent water molecules for the most stable structure since molecules are not sliding past one another in a solid.

Properties due to Water’s Polarity

1. Versatile solvent

2. Cohesion

Example: surface tension

3. Adhesion

Example: capillary action

4. Specific Heat/Heat Capacity

5. Heat of Vaporization

6. Freezing