Chapter 3: Water And Life

Question 1

Cohesion

Answer 1

The linking together of like molecules. Often through hydrogen bonding

Question 2

Adhesion

Answer 2

The clinging of one substance to another, such as water to plant cell walls.

Question 3

Surface Tension

Answer 3

A measure of how difficult it is to stretch or break the surface of a liquid.

Water has a high surface tension because the hydrogen bonds are not as stretched at the surface

Question 4

Specific Heat

Answer 4

The amount of heat that must be absorbed or lost for 1g of substance to change its temperature by 1ºC

Water has a high specific heat because most of the thermal energy absorbed by water is used to break the hydrogen bonds.

Question 5

Heat of Vaporization

Answer 5

The quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to gaseous state.

Question 6

Evaporative Cooling

Answer 6

The process in which the surface of an object becomes cooler during evaporation

Question 7

Why does ice float on liquid water?

Answer 7

Solid ice is less dense than liquid water because of hydrogen bonds. When water cools, eventually the hydrogen bonds no longer have enough energy to break and they form a crystalline structure.

Question 8

Why is water known as the universal solvent

Answer 8

Water’s versatility as a solvent can be traced to its polarity

Ions dissociate in water because of the partial charges.

Question 9

Hydrophilic

Answer 9

Having an affinity for water

Generally polar molecules and ions are hydrophilic

Question 10

Hydrophobic

Answer 10

Having no affinity for water. Tends to form droplets in water

Generally non polar molecules are hydrophobic

Question 11

Acid

Answer 11

A substance that donates hydrogen cations to a substance and decreases the pH. Increases the hydrogen ion concentration

Question 12

Base

Answer 12

A substance that accepts hydrogen ions from a solution. Lowers concentration of hydrogen ions and increases the pH

Question 13

pH

Answer 13

A measure of hydrogen ion concentration ranging in values from 0-14

Each step of the pH scale is 10x more acidic or basic than the one before it

Low numbers are acidic and high numbers are more basic

Question 14

Buffer

Answer 14

A solution that contains a weak acid and its corresponding base. A buffer minimizes changes in pH when acids or bases are added to the solution.