Chapter 3

Question 1

What are some characteristics of water?

Answer 1

Water is a molecule that supports all of life
Water is the biological medium here on earth
All organisms require water more than any other substance
3/4 of earth surface is submerged in water
The abundance of water is the main reason the earth is habitable

Question 2

What bond does a water molecule contain?

Answer 2

A hydrogen bond and due to the uneven charge distribution water is a polar molecule

Question 3

What is the benefit of water molecules being polar?

Answer 3

It allows them to form hydrogen bond with each other and contributes to the various properties water exhibits

Question 4

Each water molecule is capable of forming how many bond with other molecules

Answer 4

Four hydrogen bonds with other water molecules

Question 5

What is the first property of water that attributes H bonding?

Answer 5

Water molecules, being cohesive
Cohesion is adjoining together of many water molecules due to hydrogen bonding
Aids in giving water very structured organization
Cohesion helps pull up water through the water conducting cells of plants

Question 6

What is another property of water?

Answer 6

Water has adhesion, which is the clinging of one substance to another
Water can form hydrogen bond with other molecules, such as molecules that make up the cell wall of plants
Such as adhesion in the xylem

Question 7

What is the third property of water?

Answer 7

Surface tension, which is a measure of how hard it is to break the surface of a liquid.
It is related to cohesion,
it is used by small insects to walk across water.

Question 8

What is the fourth property of water?

Answer 8

Water can absorb or lose a large amount of heat before its own temperature is changed.
It’s attributed to its hydrogen bonding
defined as amount of heat, absorbed or loss with 1 g of substance changes its temperature by 10 Celsius.
It helps stabilize water temperatures, and because of this water can moderate air temperature

Question 9

What is the fifth property of water?

Answer 9

Water has high heat of vaporization
Defined as the amount of energy required to change 1 g of liquid to gas
Attributed to his hydrogen bond, because water has many h-bonds therefore a lot of energy is required to break

Question 10

What is the sixth and final property of water?

Answer 10

Water is a versatile solvent due to its polarity
Solvent is a dissolving agent
Solute is what is being dissolved
Almost any charge or polar molecule can be dissolved in water

Question 11

What happens when NACL is in a beaker of water

Answer 11

The oxygen in the water will be attracted to the NA plus cations
The hydrogen in water will be attracted to the CL minus anions
The salt will dissolve resulting in a solution

Question 12

Can water also interact with polar molecules, such as proteins

Answer 12

Yes

Question 13

What is a hydrophilic sub

Answer 13

Has affinity for water so substances that are ionic or polar

Question 14

What is a hydrophobic substance?

Answer 14

Does not have affinity for water, substances that are non-ionic and nonpolar

Question 15

What is an acid?

Answer 15

Any substance that increases the hydrogen ion concentration of a solution
Example HCL is an acid ,added to water then the
H+ + Cl-

Question 16

What is a base?

Answer 16

A base is any substance that reduces the hydrogen ion concentration of a solution
NH3 as a base , when added to H+ it becomes NH4+

Question 17

In pure water, how many H plus are there at 25°C?

Answer 17

There are 1.0×10 -7 M
Since this is a very small number, we we use a pH scale to express the concentration
PH= -log[H+]

Question 18

How is pH of a solution determined

Answer 18

By the relative concentration of hydrogen ions
It’s the pH is a low number > high concentration of H+
If the pH is a high number > low concentration of H+

Question 19

At what number are solutions acidic and at what number are they basic?

Answer 19

At a pH less than seven are acidic
At a pH of greater than seven basic